--source instead of --add-source for dotnet tool install dotnet-format

Author: christophwille

.github/workflows/build-ilspy.yml

@@ -48,7 +48,7 @@ jobs:
       env:
         DOTNET_FORMAT_VERSION: 10.0.100-rtm.25531.102
         DOTNET_FORMAT_SOURCE: https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet10-transport/nuget/v3/index.json
-      run: dotnet tool install -g dotnet-format --version "${{env.DOTNET_FORMAT_VERSION}}" --add-source "${{env.DOTNET_FORMAT_SOURCE}}"
+      run: dotnet tool install -g dotnet-format --version "${{env.DOTNET_FORMAT_VERSION}}" --source "${{env.DOTNET_FORMAT_SOURCE}}"
 
     - name: Install wix (locked version)
       run: dotnet tool install --global wix --version 6.0.2