Update actions/checkout action to v6 (#184)

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

Author: renovate[bot]

.github/workflows/docs.yml

@@ -26,7 +26,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Dotnet Setup
         uses: actions/setup-dotnet@v5
         with:

.github/workflows/main.yml

@@ -14,7 +14,7 @@ jobs:
   verify-workflows:
     runs-on: ubuntu-24.04
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Set up .NET SDK
       uses: actions/setup-dotnet@v5
     - run: dotnet fsi ./scripts/github-actions.fsx verify
@@ -32,7 +32,7 @@ jobs:
       DOTNET_NOLOGO: 1
       NUGET_PACKAGES: ${{ github.workspace }}/.github/nuget-packages
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Set up .NET SDK
       uses: actions/setup-dotnet@v4
       with:
@@ -50,19 +50,19 @@ jobs:
   licenses:
     runs-on: ubuntu-24.04
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: REUSE license check
       uses: fsfe/reuse-action@v5
   encoding:
     runs-on: ubuntu-24.04
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Verify encoding
       shell: pwsh
       run: scripts/Test-Encoding.ps1
   nowarn-empty:
     runs-on: ubuntu-24.04
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Verify with NoWarn as empty
       run: dotnet build /p:NoWarn='' --no-incremental

.github/workflows/release.yml

@@ -18,7 +18,7 @@ jobs:
       contents: write
     runs-on: ubuntu-24.04
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - id: version
       name: Get version
       shell: pwsh