ci: attempt to fix tests

Author: bolinocroustibat

.github/workflows/test_full.yml

@@ -14,6 +14,8 @@ on:
 jobs:
   test:
     runs-on: ubuntu-22.04
+    permissions:
+      contents: read
     strategy:
       matrix:
         python-version: ['3.8', '3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
@@ -66,7 +68,7 @@ jobs:
     steps:
       - uses: actions/checkout@v6
         with:
-          ref: ${{ github.ref }}
+          ref: ${{ github.sha }}
       - name: Debug matrix values
         run: |
           echo "Python version: ${{ matrix.python-version }}"
@@ -143,10 +145,12 @@ jobs:
 
   codestyle:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
     steps:
       - uses: actions/checkout@v6
         with:
-          ref: ${{ github.head_ref }}
+          ref: ${{ github.sha }}
       - name: Set up Python
         uses: actions/setup-python@v6
         with: