Set debconf to be noninteractive via dpkg-reconfigure

- The GitHub Actions ubuntu runner threw some permissions issues
  when I tried to set the frontend to be noninteractive by directly
  invoking the debconf command. Let's try setting debconf to be noninteractive
  via dpkg-reconfigure instead to get past this.

.github/workflows/test-dotnet-samples.yml

@@ -116,7 +116,7 @@ jobs:
             - name: Setup Microsoft Core Fonts
               run: |
                 if [ "${{ matrix.os }}" == 'ubuntu-latest' ]; then
-                  echo 'debconf debconf/frontend select Noninteractive' | debconf-set-selections
+                  sudo dpkg-reconfigure debconf -f noninteractive
                   sudo apt-get -y install ttf-mscorefonts-installer
                 fi
             - name: Build samples