Corrected syntax to use github context to access actor name

.github/workflows/ci-build.yml

@@ -83,7 +83,7 @@ jobs:
           echo ::set-env name=VERSION_NUMBER_SEM2::$(cat ./version-number.txt)${{ env.VERSION_NUMBER_SUFFIX_SEM2 }}
 
       - name: Update the nuget config with the credentials for the GitHub Package Repository
-        run: dotnet nuget update source ${{ env.NUGET_SOURCE_NAME }} --username ${{ env.GITHUB_ACTOR }} --password ${{ secrets.GITHUB_TOKEN }}
+        run: dotnet nuget update source ${{ env.NUGET_SOURCE_NAME }} --username ${{ github.actor }} --password ${{ secrets.GITHUB_TOKEN }}
 
       - name: Update the Chocolatey dependencies for scheduled builds
         if: github.event_name == 'schedule'