Bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...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] <[email protected]>

Author: dependabot[bot]

.github/workflows/build.yml

@@ -47,7 +47,7 @@ jobs:
 
     container: kambi/castle-engine-cloud-builds-tools:cge-none
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       # Setup Castle Game Engine
       - name: Castle Game Engine - Env CASTLE_ENGINE_PATH
@@ -99,7 +99,7 @@ jobs:
         ]
     runs-on: ${{ matrix.runner }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       # Setup Castle Game Engine
       - name: Castle Game Engine - Env CASTLE_ENGINE_PATH
@@ -159,7 +159,7 @@ jobs:
           cpu: cortex-a53
           base_image: raspios_lite_arm64:latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: pguyot/arm-runner-action@v2
         with:
           base_image: ${{ matrix.base_image }}
@@ -221,7 +221,7 @@ jobs:
     runs-on: ${{ matrix.host-label }}
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       # Setup Castle Game Engine
       - name: Castle Game Engine - Env CASTLE_ENGINE_PATH
@@ -273,7 +273,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: [release]
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Update Release Tag
       if: ${{ github.ref == 'refs/heads/master' }}
       run: |

.github/workflows/test-demo-models.yml

@@ -16,10 +16,10 @@ jobs:
     runs-on: ubuntu-latest
     container: kambi/castle-engine-cloud-builds-tools:cge-unstable
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
 
     - name: Checkout demo-models
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
       with:
         repository: castle-engine/demo-models
         path: demo-models