Update condition and token in github action

The github action in 'build-stable.yaml' has been updated with a new condition for release. It now triggers only if the github reference starts with 'refs/tags/'. The token has also been updated from 'GITHUB_TOKEN' to 'NAUTHILUS_RELEASE' which specifies the token to be used for release authentication.

Signed-off-by: Christian Roessner <c@roessner.co>

.github/workflows/build-stable.yaml

@@ -41,6 +41,7 @@ jobs:
 
       - name: Release
         uses: softprops/action-gh-release@v1
+        if: startsWith(github.ref, 'refs/tags/')
         with:
-          token: ${{ secrets.GITHUB_TOKEN }}
+          token: ${{ secrets.NAUTHILUS_RELEASE }}
           files: server/nauthilus-${{ matrix.goos }}-${{ matrix.goarch }}