gh-124111: test macOS CI with Tk 9

Author: ned-deily

.github/workflows/reusable-macos.yml

@@ -43,9 +43,9 @@ jobs:
         key: ${{ github.job }}-${{ env.IMAGE_OS_VERSION }}-${{ inputs.config_hash }}
     - name: Install Homebrew dependencies
       run: |
-        brew install pkg-config [email protected] xz gdbm tcl-tk@8 make
+        brew install pkg-config [email protected] xz gdbm tcl-tk@9 make
         # Because alternate versions are not symlinked into place by default:
-        brew link --overwrite tcl-tk@8
+        brew link --overwrite tcl-tk@9
     - name: Configure CPython
       run: |
         MACOSX_DEPLOYMENT_TARGET=10.15 \