[packaging] Update macs to use Mac 12

Bug: None
Change-Id: I6132f59a8a161bd51cc1df971b0d59a531ea55f2
Reviewed-on: https://flutter-review.googlesource.com/c/infra/+/28560
Reviewed-by: Godofredo Contreras <godofredoc@google.com>
Commit-Queue: Casey Hillers <chillers@google.com>
diff --git a/config/generated/flutter/luci/cr-buildbucket.cfg b/config/generated/flutter/luci/cr-buildbucket.cfg
index 87afc14..c34d53a 100644
--- a/config/generated/flutter/luci/cr-buildbucket.cfg
+++ b/config/generated/flutter/luci/cr-buildbucket.cfg
@@ -55824,7 +55824,7 @@
       name: "Mac Arm64 Flutter Beta Packaging"
       swarming_host: "chromium-swarm.appspot.com"
       dimensions: "cpu:arm"
-      dimensions: "os:Mac-11.6"
+      dimensions: "os:Mac-12"
       dimensions: "pool:luci.flutter.prod"
       exe {
         cipd_package: "flutter/recipe_bundles/flutter.googlesource.com/recipes"
@@ -55866,7 +55866,7 @@
       name: "Mac Arm64 Flutter Dev Packaging"
       swarming_host: "chromium-swarm.appspot.com"
       dimensions: "cpu:arm"
-      dimensions: "os:Mac-11.6"
+      dimensions: "os:Mac-12"
       dimensions: "pool:luci.flutter.prod"
       exe {
         cipd_package: "flutter/recipe_bundles/flutter.googlesource.com/recipes"
@@ -55973,7 +55973,7 @@
     builders {
       name: "Mac Flutter Beta Packaging"
       swarming_host: "chromium-swarm.appspot.com"
-      dimensions: "os:Mac-10.15"
+      dimensions: "os:Mac-12"
       dimensions: "pool:luci.flutter.prod"
       exe {
         cipd_package: "flutter/recipe_bundles/flutter.googlesource.com/recipes"
@@ -56014,7 +56014,7 @@
     builders {
       name: "Mac Flutter Dev Packaging"
       swarming_host: "chromium-swarm.appspot.com"
-      dimensions: "os:Mac-10.15"
+      dimensions: "os:Mac-12"
       dimensions: "pool:luci.flutter.prod"
       exe {
         cipd_package: "flutter/recipe_bundles/flutter.googlesource.com/recipes"
@@ -56055,7 +56055,7 @@
     builders {
       name: "Mac Flutter Stable Packaging"
       swarming_host: "chromium-swarm.appspot.com"
-      dimensions: "os:Mac-10.15"
+      dimensions: "os:Mac-12"
       dimensions: "pool:luci.flutter.prod"
       exe {
         cipd_package: "flutter/recipe_bundles/flutter.googlesource.com/recipes"
diff --git a/config/packaging_config.star b/config/packaging_config.star
index ae5977f..315efca 100644
--- a/config/packaging_config.star
+++ b/config/packaging_config.star
@@ -15,8 +15,8 @@
 # Global OS variables
 LINUX_OS = "Linux"
 WINDOWS_OS = "Windows"
-MAC_OS = "Mac-10.15"
-MAC_ARM64_OS = "Mac-11.6"
+MAC_OS = "Mac-12"
+MAC_ARM64_OS = "Mac-12"
 
 # Linux caches
 LINUX_DEFAULT_CACHES = [