Build(deps): bump actions/checkout from 4 to 6 (#10)

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
     name: Lint (ruff)
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup uv environment
         uses: ./.github/actions/setup-uv
@@ -28,7 +28,7 @@ jobs:
     name: Test (pytest)
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup uv environment
         uses: ./.github/actions/setup-uv
@@ -56,7 +56,7 @@ jobs:
     name: Docs (Sphinx)
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup uv environment
         uses: ./.github/actions/setup-uv