[CHORE] CI 중복 실행 방지 스크립트 추가

Author: DongChyeon

.github/workflows/android_ci.yml

@@ -15,6 +15,10 @@ on:
             - 'build.gradle'
             - 'app/**'
 
+concurrency:
+    group: ${{ github.workflow }}-${{ github.ref }}
+    cancel-in-progress: true
+
 jobs:
   build:
     runs-on: ubuntu-latest