Auto-bump package version in Github Actions

.github/workflows/python-publish.yml

@@ -23,6 +23,20 @@ jobs:
       uses: actions/setup-python@v2
       with:
         python-version: '3.x'
+    - name: Auto-bump package version
+      run: |
+        # Get 1.2.3 from refs/tags/v1.2.3
+        VERSION=$(echo $GITHUB_REF | sed 's#.*/v##')
+        PLACEHOLDER='__version__ = "develop"'
+        VERSION_FILE='onaws/__init__.py'
+
+        # Ensure that placeholder exists. If grep doesn't find the placeholder,
+        # it exits with exit code 1 and GitHub Actions aborts the build
+        grep "$PLACEHOLDER" "$VERSION_FILE"
+
+        # Replace with actual version
+        sed -i "s/$PLACEHOLDER/__version__ = \"${VERSION}\"/g" "$VERSION_FILE"
+      shell: bash
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip