Fully qualify git submodules

In order for internal acls to work, this needs to include the '.git' suffix.

.gitmodules

diff --git a/.gitmodules b/.gitmodules
index 5942031..df056a9 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -8,5 +8,5 @@
 	ignore = dirty
 [submodule "third_party/abseil-cpp"]
 	path = third_party/abseil-cpp
-	url = https://github.com/abseil/abseil-cpp
+	url = https://github.com/abseil/abseil-cpp.git
 	branch = lts_2022_06_23