Add timeout-minutes to CI builds

Author: seratch

.github/workflows/ci-build.yml

@@ -10,6 +10,7 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    timeout-minutes: 10
     strategy:
       matrix:
         python-version: ['3.6', '3.7', '3.8', '3.9']