Set Github actions build timeout to 30 min

Sometimes a runner, especially the Windows one, goes wrong and runs
until the default timeout of 6 hours is hit. Introduce a timeout of 30
minutes to avoid occupying the runner for so long needlessly.

Author: TheZoker

.github/workflows/ci.yaml

@@ -5,6 +5,7 @@ on: [push, pull_request]
 jobs:
   ci:
     runs-on: ${{ matrix.os }}
+    timeout-minutes: 30
     strategy:
       fail-fast: false
       matrix:
@@ -20,7 +21,7 @@ jobs:
       with:
         node-version: 12
     - name: Build
-      run: | 
+      run: |
         npm ci
         npm run init
         npm run build