GitHub Workflows security hardening (#1451)

Author: sashashura

.github/workflows/ci.yml

@@ -11,6 +11,9 @@ env:
   GIT_BRANCH: ${{ github.ref }}
   COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}
 
+permissions:
+  contents: read # to fetch code (actions/checkout)
+
 jobs:
   linting:
     runs-on: ubuntu-latest

.github/workflows/publish.yml

@@ -4,6 +4,8 @@ on:
   release:
     types: [published]
 
+permissions:
+  contents: read  # to checkout the code (actions/checkout)
 jobs:
   build:
     name: Publish to Rubygems

.github/workflows/refresh_team_page.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches: [ main ]
 
+permissions: {}
 jobs:
   build:
     name: Refresh Contributors Stats