add explicit permissions to github workflow files

Author: nunoplopes

.github/workflows/format.yml

@@ -5,6 +5,9 @@ on: [push, pull_request]
 jobs:
   format:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+
     steps:
       - name: Checkout code
         uses: actions/checkout@v6

.github/workflows/run-tests.yml

@@ -13,6 +13,9 @@ jobs:
     runs-on: ${{ matrix.os }}
     name: Run Tests (${{ matrix.os }}, ${{ matrix.build_type }})
 
+    permissions:
+      contents: read
+
     steps:
       - name: Checkout code
         uses: actions/checkout@v6