ci: add explicit permissions to workflow files (#6)

Author: robertodauria

.github/workflows/coverage.yml

@@ -5,6 +5,9 @@ on:
     branches:
       - "main"
 
+permissions:
+  contents: read
+
 jobs:
   coverage:
     runs-on: ubuntu-latest

.github/workflows/test.yml

@@ -4,6 +4,10 @@ on:
   push:
     branches:
       - "main"
+
+permissions:
+  contents: read
+
 jobs:
   build_and_run_tests:
     runs-on: "${{ matrix.os }}"