Update actions/checkout action to v6 (#218)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/check_pr.yaml

@@ -49,7 +49,7 @@ jobs:
       pr_number: ${{ steps.pr-number.outputs.pr }}
       action: ${{ (github.event_name == 'issues' || github.event_name == 'issue_comment') && steps.pr-number.outputs.action || inputs.action }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           persist-credentials: false
 
@@ -149,7 +149,7 @@ jobs:
           key: issues-dump-v2-${{ github.run_id }}
           restore-keys: issues-dump-v2-
 
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         if: ${{ steps.restore-issues.outputs.cache-matched-key == '' }}
         with:
           persist-credentials: false
@@ -184,7 +184,7 @@ jobs:
         shard: [0, 1]
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           persist-credentials: false
       - uses: astral-sh/setup-uv@v7
@@ -250,7 +250,7 @@ jobs:
       issues: write
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           persist-credentials: false
       - uses: astral-sh/setup-uv@v7
@@ -323,7 +323,7 @@ jobs:
       result_run_simple_3: ${{ steps.run-bench.outputs.result_run_simple_3 }}
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           persist-credentials: false
           repository: python/mypy
@@ -451,7 +451,7 @@ jobs:
     permissions:
       issues: write
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           persist-credentials: false
       - name: Clear body

.github/workflows/close_old_issues.yaml

@@ -14,7 +14,7 @@ jobs:
     permissions:
       issues: write
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           persist-credentials: false
       - name: List open issues

.github/workflows/download_issues.yaml

@@ -17,7 +17,7 @@ jobs:
   sync:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           persist-credentials: false
       - uses: astral-sh/setup-uv@v7

.github/workflows/lint.yaml

@@ -12,7 +12,7 @@ jobs:
   pre-commit:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           persist-credentials: false
       - uses: actions/setup-python@v6
@@ -27,7 +27,7 @@ jobs:
     name: mypy
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           persist-credentials: false
       - uses: astral-sh/setup-uv@v7