Merge upstream fix for osx-gcc job (#650)

I noticed the `osx-gcc` job failing in #647 so I found this upstream fix
from @peff. Merging now to unblock PR builds in `microsoft/git`.

.github/workflows/main.yml

@@ -283,8 +283,7 @@ jobs:
             cc: clang
             pool: macos-13
           - jobname: osx-gcc
-            cc: gcc
+            cc: gcc-13
-            cc_package: gcc-13
             pool: macos-13
           - jobname: linux-gcc-default
             cc: gcc

ci/install-dependencies.sh

@@ -34,8 +34,6 @@ macos-*)
 	export HOMEBREW_NO_AUTO_UPDATE=1 HOMEBREW_NO_INSTALL_CLEANUP=1
 	# Uncomment this if you want to run perf tests:
 	# brew install gnu-time
-	test -z "$BREW_INSTALL_PACKAGES" ||
-	brew install $BREW_INSTALL_PACKAGES
 	brew link --force gettext
 
 	mkdir -p "$P4_PATH"