build: allow manual workflow_dispatch trigger.

Author: tmds

.github/workflows/build.yaml

@@ -1,5 +1,5 @@
 name: Build
-on: [push, pull_request]
+on: [push, pull_request, workflow_dispatch]
 jobs:
   build:
     runs-on: ubuntu-22.04
@@ -49,4 +49,4 @@ jobs:
           dotnet nuget push -s https://www.myget.org/F/tmds/api/v2/package -k "${{ secrets.NUGET_APIKEY }}" src/Tmds.DBus.Protocol/*.nupkg
           dotnet nuget push -s https://www.myget.org/F/tmds/api/v2/package -k "${{ secrets.NUGET_APIKEY }}" src/Tmds.DBus.Generator/*.nupkg
           dotnet nuget push -s https://www.myget.org/F/tmds/api/v2/package -k "${{ secrets.NUGET_APIKEY }}" src/Tmds.DBus.Tool/*.nupkg
-        if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' }}
+        if: ${{ (github.event_name == 'push' || github.event_name == 'workflow_dispatch') && github.ref == 'refs/heads/main' }}