CI: Guard publishing to nuget based on the branch

The CI workflow will only publish to nuget if running on the master or
geewallet-payments branches. The reference to the geewallet-payments
branch can be removed once the branch is merged to master.

.github/workflows/ci.yml

@@ -24,6 +24,9 @@ jobs:
     - name: Upload BouncyCastle nuget package
       run: |
         cd $GITHUB_WORKSPACE/src/DotNetLightning.Core
-        if [ ${{ secrets.NUGET_API_KEY }} ]; then
+        # NOTE:
+        # the geewallet-payments branch reference here can be removed once this
+        # is merged to master
+        if [ ${{ secrets.NUGET_API_KEY }} ] && [ $GITHUB_REF == "refs/heads/master" -o $GITHUB_REF == "refs/heads/geewallet-payments" ]; then
             dotnet nuget push ./bin/Release/DotNetLightning.Kiss.1*.nupkg -k ${{ secrets.NUGET_API_KEY }} -s https://api.nuget.org/v3/index.json
         fi