Update dotnet.yml

Author: pjoiner

.github/workflows/dotnet.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2.5.0
+    - uses: actions/checkout@v3
     - name: Setup .NET
       uses: actions/[email protected]
       with: