Update actions/checkout action to v6

Reviewed-on: #5

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
   lint-and-security:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
@@ -32,7 +32,7 @@ jobs:
   tests-and-coverage:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
       
       - name: Set up Python
         uses: actions/setup-python@v5

.github/workflows/codeql.yml

@@ -1,36 +0,0 @@
-name: "CodeQL Analysis"
-
-on:
-  push:
-    branches: [ main ]
-  pull_request:
-    branches: [ main ]
-  schedule:
-    - cron: '30 1 * * 0' # Weekly scan
-
-jobs:
-  analyze:
-    name: Analyze
-    runs-on: ubuntu-latest
-    permissions:
-      security-events: write
-
-    strategy:
-      fail-fast: false
-      matrix:
-        language: [ 'python' ]
-
-    steps:
-    - name: Checkout repository
-      uses: actions/checkout@v4
-
-    - name: Initialize CodeQL
-      uses: github/codeql-action/init@v3
-      with:
-        languages: ${{ matrix.language }}
-
-    - name: Autobuild
-      uses: github/codeql-action/autobuild@v3
-
-    - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v3