Targets ubuntu 22.04, which is the version from the last successful build.

Author: Richard Bennett

.github/workflows/pr-checks.yml

@@ -49,7 +49,7 @@ jobs:
     strategy:
       matrix:
         dotnet-version: [ '6.0', '8.0']
-        os: [windows-latest, ubuntu-latest]              
+        os: [windows-latest, ubuntu-22.04]              
 
     runs-on: ${{ matrix.os }}       
 
@@ -62,7 +62,7 @@ jobs:
 
     # Install .NET Core
     - name: Install .NET ${{ matrix.dotnet-version }}
-      if: ${{ matrix.os == 'ubuntu-latest' }}
+      if: ${{ matrix.os == 'ubuntu-22.04' }}
       uses: actions/setup-dotnet@v4
       with:
         dotnet-version: ${{ matrix.dotnet-version }}