Update build.yml

.github/workflows/build.yml

@@ -1,16 +1,23 @@
 name: build
 
-on: [push, pull_request]
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+permissions:
+  contents: read
 
 jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
-    - name: Set up Python 3.9
-      uses: actions/setup-python@v1
+    - uses: actions/checkout@v3
+    - name: Set up Python 3.10
+      uses: actions/setup-python@v3
       with:
-        python-version: 3.9
+        python-version: "3.10"
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip