chore(deps): update actions/checkout action to v6 (#226)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/release-nuget.yaml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-22.04
     environment: Release
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Setup .NET
         uses: actions/setup-dotnet@v5
         with:

.github/workflows/test-dotnet.yml

@@ -22,7 +22,7 @@ jobs:
   test-dotnet:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-dotnet@v5
         with:
           dotnet-version: |