ci: bump actions/checkout to v7

Bumps actions/checkout from v6 to v7 across CI, CodeQL and PyPI publish workflows.

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Set up Python 3.12
         uses: actions/setup-python@v6
@@ -59,7 +59,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v6

.github/workflows/codeql.yml

@@ -25,7 +25,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v4

.github/workflows/publish-pypi.yml

@@ -22,7 +22,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Set up Python 3.12
         uses: actions/setup-python@v6