Add permissions to workflows

.github/workflows/build_test.yml

@@ -2,6 +2,9 @@ name: Build test
 
 on: [push, pull_request]
 
+permissions:
+  contents: read
+
 jobs:
   test_iOS:
     name: Test iOS on ${{ matrix.os }}

.github/workflows/issue_labeler.yml

@@ -4,6 +4,10 @@ on:
   issues:
     types: [opened]
 
+permissions:
+  contents: read
+  issues: write
+
 jobs:
   label:
     runs-on: ubuntu-latest

.github/workflows/pub_dry_run.yml

@@ -2,6 +2,9 @@ name: Pub Publish dry run
 
 on: [push]
 
+permissions:
+  contents: read
+
 jobs:
   publish:
 

.github/workflows/pub_publish.yml

@@ -4,6 +4,9 @@ on:
   release:
     types: [published]
 
+permissions:
+  contents: read
+
 jobs:
   publish: