[CI] Increase timeout because platformio download is slow

Author: Rotzbua

.github/workflows/test.platformio.yml

@@ -5,7 +5,7 @@ on: [push, pull_request]
 jobs:
   build:
     runs-on: ubuntu-20.04
-    timeout-minutes: 10
+    timeout-minutes: 20
     strategy:
       fail-fast: false
       max-parallel: 20