Add workflow for Homebrew release automation

.github/workflows/brew-update.yml

@@ -0,0 +1,43 @@
+# This workflow checks to see if the `kyokan-bob` package in
+# Homebrew is updated to the latest release version. If it
+# is not, then it will automatically open a PR to update it
+# with the proper details in the Homebrew/homebrew-cask repo.
+
+# Triggers on its own every time there's a new release, and
+# no human input should thus be required to maintain it.
+# Can also be run as a manual Action if necessary.
+
+# If forking Homebrew/homebrew-cask is required to open the
+# PR, a forked repo will get placed under the 'kyokan' org
+# and get merged to Homebrew from there.
+
+# A personal access token of an org member with write access,
+# stored as repository secret named BARREL_ROLL, is required.
+# The only scope needed for that token is `public_repo`.
+# PR's generated by this workflow will be made by that user.
+
+name: Homebrew Package Update
+
+on:
+  release: { types: released }
+  workflow_dispatch:
+
+jobs:
+  kyokan-bob:
+    runs-on: macos-latest
+    steps:
+    - name: bump-cask-pr kyokan-bob
+      uses: macauley/action-homebrew-bump-cask@v1.0.0
+      with:
+        # Required, custom GitHub access token with only the 'public_repo' scope enabled
+        token: ${{secrets.BARREL_ROLL}}
+        # Optional, will create tap repo fork in organization
+        org: kyokan
+        # Bump all outdated casks in this tap (if 'cask' is empty)
+        tap: homebrew/cask
+        # Bump only these casks if outdated
+        cask: kyokan-bob
+        # Optional, if don't want to check for already open PRs
+        force: false # true
+        # Need to set this input if want to use `brew livecheck`
+        livecheck: true