chore(deps): update actions/checkout action to v6

Author: renovate-bot

.github/workflows/release.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Install uv
         uses: astral-sh/setup-uv@v7

.github/workflows/tests.yml

@@ -32,7 +32,7 @@ jobs:
       run:
         shell: bash
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Install uv
         uses: astral-sh/setup-uv@v7