Add github action to create PR against homebrew-core on release

Author: hannes-steffenhagen-diffblue

.github/workflows/release-packages.yaml

@@ -0,0 +1,18 @@
+on:
+  release:
+    types: [created]
+
+name: Upload additional release assets
+jobs:
+  homebrew-pr:
+    runs-on: macos-10.15
+    steps:
+      - name: Get release tag name
+        # The GITHUB_REF we get has refs/tags/ in front of the tag name so we
+        # strip that here
+        run: echo "::set-env name=RELEASE_TAG::${GITHUB_REF/refs\/tags\/}"
+      - name: Create homebrew PR
+        run: |
+          brew bump-formula-pr --tag "$RELEASE_TAG" --revision "$GITHUB_SHA" cbmc
+        env:
+          HOMEBREW_GITHUB_API_TOKEN: ${{ secrets.DB_CI_CPROVER_ACCESS_TOKEN }}