Replace PAT with GHA built-in secret in 'release' job (#1428)

Signed-off-by: Ivan Sim <ivan.sim@kasten.io>

Co-authored-by: Pavan Navarathna <6504783+pavannd1@users.noreply.github.com>

.github/workflows/main.yaml

@@ -75,15 +75,17 @@ jobs:
     runs-on: ubuntu-20.04
     needs: [test, build]
     if: github.ref_name == 'master' || startsWith(github.ref, 'refs/tags')
+    permissions:
+      packages: write
     steps:
     - uses: actions/download-artifact@v3
       with:
         name: src
     - uses: docker/login-action@v1
       with:
         registry: ghcr.io
-        username: ${{ secrets.GH_USERNAME }}
-        password: ${{ secrets.GH_TOKEN }}
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
     - run: tar -xvf ./src.tar.gz
     - run: make release-snapshot
     - run: ./build/push_images.sh