build: add GitHub Action for release-please (#2)

Author: feeph

.github/workflows/release-please.yaml

@@ -0,0 +1,42 @@
+---
+#
+# automated release numbering using release-please
+#  - https://github.com/googleapis/release-please
+#  - https://github.com/googleapis/release-please-action
+#
+
+on:
+  push:
+    branches:
+      - main
+      - master
+
+# verify "Actions" settings:
+# https://github.com/feeph/libi2c-python/settings/actions
+#  - [x] "Allow GitHub Actions to create and approve pull requests"
+permissions:
+  contents: write
+  pull-requests: write
+
+name: release-please
+
+jobs:
+  release-please:
+    runs-on: ubuntu-latest
+    environment: release-please
+    steps:
+      - name: Create a release
+        uses: googleapis/release-please-action@v4
+        with:
+          # do NOT use 'secrets.GITHUB_TOKEN':
+          # ---------------------------------------------------------------
+          # When you use the repository's GITHUB_TOKEN to perform tasks,
+          # events triggered by the GITHUB_TOKEN will not create a new
+          # workflow run. This prevents you from accidentally creating
+          # recursive workflow runs.
+          # ---------------------------------------------------------------
+          # required permissions:
+          #  - Contents:      Read and write
+          #  - Pull requests: Read and write
+          token: ${{ secrets.RELEASE_PLEASE_TOKEN }}
+          target-branch: ${{ github.ref_name }}