Update build.yml

Author: changeyoung98

.github/workflows/build.yml

@@ -7,7 +7,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest]
-        python-version: ['3.7']
+        python-version: ['3.8']
         node-version: ['14']
     steps:
       - name: Checkout