fix: add contents write permission to release workflow (#32)

The github-actions[bot] user requires explicit write permissions to push git tags.
Without this, the workflow fails with a 403 error when attempting to push tags.

Author: hugoduncan

.github/workflows/release.yml

@@ -14,6 +14,8 @@ jobs:
     runs-on: ubuntu-latest
     environment: Release
     if: github.ref == 'refs/heads/master'
+    permissions:
+      contents: write
 
     steps:
     - name: Checkout code