build(deps): 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/documentation.yml

@@ -50,7 +50,7 @@ jobs:
 
     steps:
       - name: Get source code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Set up Python
         uses: actions/setup-python@v6

.github/workflows/linter.yml

@@ -30,7 +30,7 @@ jobs:
       options: --user root
     steps:
       - name: Get source code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Check PyQt5 to PyQt6 compatibility.
         run: |

.github/workflows/package_and_release.yml

@@ -31,7 +31,7 @@ jobs:
 
     steps:
       - name: Get source code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup Python
         uses: actions/setup-python@v6
@@ -69,7 +69,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup Python
         uses: actions/setup-python@v6
@@ -131,7 +131,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup Python
         uses: actions/setup-python@v6