use sed to downgrade gradle as even the gradle wrapper requires java 17

Author: TheSnoozer

.github/workflows/default-tests.yml

@@ -54,7 +54,7 @@ jobs:
           java-version: ${{ matrix.java_version }}
           java-package: jdk
       - name: Downgrade gradle wrapper
-        run: ./gradlew wrapper --gradle-version 8.14.4
+        run: sed -i 's/gradle-[0-9.]*-\(bin\|all\)\.zip/gradle-8.14.4-\1.zip/' gradle/wrapper/gradle-wrapper.properties
       - name: Build with Gradle
         run: ./gradlew clean build