simplify

Signed-off-by: Olivier Lamy <olamy@apache.org>
diff --git a/.github/workflows/maven.yml b/.github/workflows/maven.yml
index 972cbe2..abc6a5e 100644
--- a/.github/workflows/maven.yml
+++ b/.github/workflows/maven.yml
@@ -17,13 +17,7 @@
 
 name: GitHub CI
 
-on:
-  push:
-    branches:
-    - master
-  pull_request:
-    branches:
-    - master
+on: [push, pull_request]
 
 jobs:
   build: