Run the build workflow when itself has changed

.github/workflows/build.yml

@@ -3,6 +3,7 @@ name: Build
 on:
   push:
     paths:
+      - .github/workflows/build.yml
       - build.gradle
       - settings.gradle
       - src/**
@@ -14,18 +15,8 @@ jobs:
   build:
     runs-on: antville
 
-    strategy:
-      matrix:
-        java: [11, 17, 21]
-
     steps:
       - uses: actions/checkout@v4
 
-      - name: Set up Java
-        uses: https://github.com/actions/setup-java@v4
-        with:
-          distribution: temurin
-          java-version: ${{ matrix.java }}
-
       - name: Compile with Gradle
         run: ./gradlew :compileJava