Make mvnw executable

Author: PhilWakelin

.github/workflows/main.yml

@@ -25,6 +25,8 @@ jobs:
           java-version: ${{ matrix.jdk }}
           distribution: "semeru"
           cache: maven
+      - name: Make mvnw executable
+        run: chmod +x ./mvnw
       - name: Build with Maven
         run: ./mvnw --batch-mode --update-snapshots --file pom.xml -Djava.version=${{ matrix.jdk }} verify