Try to fix release workflow not picking up venv

Author: piotr-grodek-dsai

.github/workflows/release.yml

@@ -25,10 +25,13 @@ jobs:
         run: python -m pip install -U build
 
       - name: Bump version as release
-        run: ./bump_version.sh release
+        run: |
+          source venv/bin/activate
+          ./bump_version.sh release
 
       - name: Build package
         run: |
+          source venv/bin/activate
           python -m build
 
       - name: Publish package distributions to PyPI