Bump upb version and refactor python compatibility.

This pulls in updates to system_python, which allows for better handling of our non-hermetic setup.  Specifically, our python tests are marked incompatible on systems without a python installation.  This will cause them to get skipped by wildcard expansions (which is why we add 1 explicit target to the kokoro builds).

PiperOrigin-RevId: 492286518
diff --git a/python/BUILD.bazel b/python/BUILD.bazel
index 56d8c8a..d40e76a 100644
--- a/python/BUILD.bazel
+++ b/python/BUILD.bazel
@@ -12,7 +12,7 @@
 load("//:protobuf.bzl", "internal_py_proto_library")
 load("//build_defs:cpp_opts.bzl", "COPTS")
 load("//conformance:defs.bzl", "conformance_test")
-load(":internal.bzl", "internal_copy_files")
+load(":internal.bzl", "internal_copy_files", "internal_py_test")
 
 py_library(
     name = "protobuf_python",
@@ -256,149 +256,111 @@
     ],
 )
 
-py_test(
+internal_py_test(
     name = "descriptor_database_test",
     srcs = ["google/protobuf/internal/descriptor_database_test.py"],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "descriptor_pool_test",
     srcs = ["google/protobuf/internal/descriptor_pool_test.py"],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "descriptor_test",
     srcs = ["google/protobuf/internal/descriptor_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "field_mask_test",
     srcs = ["google/protobuf/internal/field_mask_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "generator_test",
     srcs = ["google/protobuf/internal/generator_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "import_test",
     srcs = ["google/protobuf/internal/import_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "json_format_test",
     srcs = ["google/protobuf/internal/json_format_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "keywords_test",
     srcs = ["google/protobuf/internal/keywords_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "message_factory_test",
     srcs = ["google/protobuf/internal/message_factory_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "message_test",
     srcs = ["google/protobuf/internal/message_test.py"],
     data = glob(["testdata/golden_pickle_*"]) + [
         "//src/google/protobuf:testdata",
     ],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "numpy_test",
     srcs = ["google/protobuf/internal/numpy_test.py"],
-    imports = ["."],
     deps = [
-        ":python_test_lib",
         requirement("numpy"),
     ],
 )
 
-py_test(
+internal_py_test(
     name = "proto_builder_test",
     srcs = ["google/protobuf/internal/proto_builder_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "reflection_test",
     srcs = ["google/protobuf/internal/reflection_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "service_reflection_test",
     srcs = ["google/protobuf/internal/service_reflection_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "symbol_database_test",
     srcs = ["google/protobuf/internal/symbol_database_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "text_encoding_test",
     srcs = ["google/protobuf/internal/text_encoding_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "text_format_test",
     srcs = ["google/protobuf/internal/text_format_test.py"],
     data = ["//src/google/protobuf:testdata"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "unknown_fields_test",
     srcs = ["google/protobuf/internal/unknown_fields_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "well_known_types_test",
     srcs = ["google/protobuf/internal/well_known_types_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
-py_test(
+internal_py_test(
     name = "wire_format_test",
     srcs = ["google/protobuf/internal/wire_format_test.py"],
-    imports = ["."],
-    deps = [":python_test_lib"],
 )
 
 cc_library(
@@ -410,7 +372,7 @@
     ],
 )
 
-py_test(
+internal_py_test(
     name = "python_version",
     srcs = ["python_version.py"],
 )
@@ -420,6 +382,7 @@
     env = {"PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": "python"},
     failure_list = "//conformance:failure_list_python.txt",
     target_compatible_with = select({
+        "@system_python//:none": ["@platforms//:incompatible"],
         ":use_fast_cpp_protos": ["@platforms//:incompatible"],
         "//conditions:default": [],
     }),
@@ -433,6 +396,7 @@
     env = {"PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": "cpp"},
     failure_list = "//conformance:failure_list_python.txt",
     target_compatible_with = select({
+        "@system_python//:none": ["@platforms//:incompatible"],
         ":use_fast_cpp_protos": [],
         "//conditions:default": ["@platforms//:incompatible"],
     }),