build: Update Gradle from JDK21 to JDK25 in Dockerfile

Author: thorlauridsen

docker/Dockerfile

@@ -1,5 +1,5 @@
 # Stage 1: Build the application using a Gradle image with JDK.
-FROM gradle:9.2.1-jdk21-corretto AS builder
+FROM gradle:9.2.1-jdk25-corretto AS builder
 WORKDIR /home/gradle/project
 
 # Copy Gradle files from the correct locations.