chore(builds): upgrade minimum macOS version from 11 to 12

Builds using macOS 11 just takes a stupidly long time as, as Homebrew
seems to have dropped support, meaning all homebrew dependencies are
installed from source, rather than get installed from bottles.

Hence let's try upgrading minimum macOS version from 11 (Big Sur), to
12 (Monteray).

.github/workflows/_release.yml

@@ -8,7 +8,7 @@ on:
         description: GitHub Actions runner OS
         type: string
         required: false
-        default: "macos-11"
+        default: "macos-12"
       plan_artifact:
         description: Name of artifact containing a emacs-builder plan yaml file
         type: string
@@ -21,6 +21,11 @@ on:
         description: "Test build name"
         type: string
         required: false
+      update_casks:
+        description: "Update casks in homebrew tap?"
+        type: boolean
+        required: true
+        default: true
     secrets:
       TAP_REPO_TOKEN:
         description: Personal Access Token for Homebrew Tap repo
@@ -57,7 +62,10 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       - name: Trigger update casks workflow in homebrew tap
-        if: ${{ steps.dmg.outputs.result != 'fail' && inputs.test_build_name == '' }}
+        if: >-
+          steps.dmg.outputs.result != 'fail' &&
+          inputs.test_build_name == '' &&
+          inputs.update_casks
         run: >-
           gh workflow run --repo jimeh/homebrew-emacs-builds update-casks.yml
         env: