Bump actions/checkout from 4 to 6 (#382)

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/build.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v5
       with:

.github/workflows/codeql-analysis.yml

@@ -14,7 +14,7 @@ jobs:
     steps:
       - name: Checkout repository
         id: checkout_repo
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Initialize CodeQL
         id: init_codeql

.github/workflows/publish.yml

@@ -10,7 +10,7 @@ jobs:
     name: list Ardalis.GuardClauses on nuget.org
     runs-on: windows-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       # Required for a specific dotnet version that doesn't come with ubuntu-latest / windows-latest
       # Visit bit.ly/2synnZl to see the list of SDKs that are pre-installed with ubuntu-latest / windows-latest