chore: update github action workflow permissions

Author: parthea

.github/workflows/docs.yml

@@ -2,6 +2,10 @@ on:
   pull_request:
     branches:
       - main
+
+permissions:
+  contents: read
+
 name: docs
 jobs:
   docs:

.github/workflows/lint.yml

@@ -2,6 +2,10 @@ on:
   pull_request:
     branches:
       - main
+
+permissions:
+  contents: read
+
 name: lint
 jobs:
   lint:

.github/workflows/mypy.yml

@@ -2,6 +2,10 @@ on:
   pull_request:
     branches:
       - main
+
+permissions:
+  contents: read
+
 name: mypy
 jobs:
   mypy:

.github/workflows/unittest.yml

@@ -5,6 +5,9 @@ on:
     branches:
       - main
 
+permissions:
+  contents: read
+
 jobs:
   run-unittests:
     name: unit${{ matrix.option }}-${{ matrix.python }}