Update gradle Docker tag to v7

renovate[bot] · web-flow · commit 94f785f69343 · 2022-11-20T15:00:14.000Z
diff --git a/Dockerfile b/Dockerfile
@@ -1,4 +1,4 @@
-FROM gradle:6.0-jdk8 as builder
+FROM gradle:7.5-jdk8 as builder
 WORKDIR /workspace
 COPY / /workspace/
 RUN gradle build
