Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/build.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Setup .NET Core
         uses: actions/setup-dotnet@v5
         with:

.github/workflows/release.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Setup .NET Core
         uses: actions/setup-dotnet@v5
         with:

.github/workflows/test.yml

@@ -15,7 +15,7 @@ jobs:
       pull-requests: write
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Setup .NET Core
         uses: actions/setup-dotnet@v5
         with: