Bump actions/checkout from 4 to 6

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>

Author: dependabot[bot]

.github/workflows/build-dotnet.yaml

@@ -1,4 +1,4 @@
-name: Build .NET
+name: Build .NET
 
 on:
   workflow_call:
@@ -15,7 +15,7 @@ jobs:
       NUGET_PACKAGES: ${{ github.workspace }}/.nuget/packages
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup .NET
         uses: actions/setup-dotnet@v4

.github/workflows/main.yaml

@@ -1,4 +1,4 @@
-name: Build & Test (Main)
+name: Build & Test (Main)
 
 on:
   push:
@@ -22,7 +22,7 @@ jobs:
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           sparse-checkout: .
       - name: Generate variables

.github/workflows/release.yaml

@@ -19,7 +19,7 @@ jobs:
       is_prerelease: ${{ steps.version.outputs.is_prerelease }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           sparse-checkout: build
 
@@ -49,7 +49,7 @@ jobs:
       NUGET_PACKAGES: ${{ github.workspace }}/.nuget/packages
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup .NET
         uses: actions/setup-dotnet@v4