ci: scope down GitHub Token permissions (#212)

* ci: scope down permissions for colab.yml

* ci: scope down permissions for canary_d2l.yml

* ci: scope down permissions for pr_notebook.yml

Author: AdnaneKhan

.github/workflows/canary_d2l.yml

@@ -6,6 +6,9 @@ on:
     - cron:  '0 9 * * *'
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
   canary-test:
     runs-on: ${{ matrix.os }}

.github/workflows/colab.yml

@@ -6,6 +6,9 @@ on:
     - cron:  '0 9 * * 1'
   workflow_dispatch:
 
+permissions:
+  contents: write
+
 jobs:
   sync:
     runs-on: ubuntu-latest

.github/workflows/pr_notebook.yml

@@ -10,6 +10,9 @@ on:
       - "**.css"
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
   build:
     runs-on: ubuntu-latest