Add permissions to all workflows (#5255)

.github/workflows/mypy_primer.yml

@@ -4,6 +4,9 @@ on:
   # Only run on PR, since we diff against master
   pull_request:
 
+permissions:
+  contents: read
+
 jobs:
   mypy_primer:
     name: Run

.github/workflows/mypy_primer_comment.yml

@@ -8,6 +8,9 @@ on:
   # commit, wait till it's completed, and download and post the diff.
   pull_request_target:
 
+permissions:
+  contents: read
+
 jobs:
   mypy_primer:
     name: Comment

.github/workflows/stubtest-unused-whitelist.yml

@@ -5,6 +5,10 @@ on:
   schedule:
     - cron: '0 4 * * SAT'
 
+permissions:
+  contents: read
+  pull-requests: write
+
 jobs:
   stubtest:
     if: github.repository == 'python/typeshed'

.github/workflows/tests.yml

@@ -4,6 +4,9 @@ on:
   push:
   pull_request:
 
+permissions:
+  contents: read
+
 jobs:
   file-consistency:
     name: Check file consistency