Bump and pin the base layers, making them uniform across java images (#201)

Author: IsaacG

Dockerfile

@@ -1,10 +1,10 @@
-FROM docker.io/library/gradle:9.5.0-jdk25 AS build
+FROM gradle:9.5.0-jdk25@sha256:03305b464e024b29cfaad1c4a41fed61d06d15453176d2180f65bd4358b789a6 AS build
 
 WORKDIR /app
 COPY --chown=gradle:gradle . /app
 RUN gradle -i --stacktrace clean build
 
-FROM docker.io/library/eclipse-temurin:25.0.1_8-jdk
+FROM eclipse-temurin:25.0.3_9-jdk@sha256:e23592541431eaeef5c13c84c21db71f97cdca0e70181ea6222ec9bccac24f6c
 
 WORKDIR /opt/test-runner
 COPY bin/run.sh bin/run.sh