Update actions/checkout action to v6

| datasource  | package          | from | to     |
| ----------- | ---------------- | ---- | ------ |
| github-tags | actions/checkout | v4   | v6.0.2 |

Author: renovate[bot]

.github/workflows/linter.yaml

@@ -16,7 +16,7 @@ jobs:
 
     steps:
       - name: Checkout Code
-        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
           fetch-depth: 0
 

.github/workflows/mkdocs-build.yaml

@@ -16,7 +16,7 @@ jobs:
 
     steps:
       - name: Checkout Code
-        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
           fetch-depth: 0