ci: add GitHub token permissions (#92999)

.github/workflows/build.yml

@@ -22,6 +22,9 @@ on:
     - '3.8'
     - '3.7'
 
+permissions:
+  contents: read
+
 jobs:
   check_source:
     name: 'Check for source changes'

.github/workflows/build_msi.yml

@@ -23,6 +23,9 @@ on:
     paths:
     - 'Tools/msi/**'
 
+permissions:
+  contents: read
+
 jobs:
   build_win32:
     name: 'Windows (x86) Installer'

.github/workflows/doc.yml

@@ -24,6 +24,9 @@ on:
     - 'Doc/**'
     - 'Misc/**'
 
+permissions:
+  contents: read
+
 jobs:
   build_doc:
     name: 'Docs'

.github/workflows/new-bugs-announce-notifier.yml

@@ -5,6 +5,9 @@ on:
     types:
       - opened
 
+permissions:
+  issues: read
+
 jobs:
   notify-new-bugs-announce:
     runs-on: ubuntu-latest
@@ -39,7 +42,7 @@ jobs:
                 assignee : issue.data.assignees.map(assignee => { return assignee.login }),
                 body   : issue.data.body
               };
-            
+
               const data = {
                 from: "CPython Issues <github@mg.python.org>",
                 to: "new-bugs-announce@python.org",