deps: Update actions/checkout action to version 6

Updates-dependency: actions/checkout
Updates-dependency-from-version: v3.6.0
Updates-dependency-to-version: v6.0.3

Author: renovate[bot]

.github/workflows/update-nuget-lock-file.yml

@@ -17,7 +17,7 @@ jobs:
         echo "DOTNET_SKIP_FIRST_TIME_EXPERIENCE=1" >> $GITHUB_ENV
 
     - name: Check out repo
-      uses: actions/checkout@v3
+      uses: actions/checkout@v6
       with:
         fetch-depth: 0
         submodules: true