Pin exact versions of images and actions

Floating tags (17-alpine, 3.4-slim, nginx:alpine, :latest, :debug, @v7)
change under a deploy without anyone deciding it: the storage deploy
moved Postgres to 17.12 on its own because of postgres:17-alpine. Pin
every image and action to its exact current version, so each change
arrives as a reviewed Renovate PR and a rollback is a revert.

Assisted-by: Claude:opus-5-5

ansible/roles/minecraft/files/docker-compose.yml

@@ -1,6 +1,6 @@
 services:
   minecraft:
-    image: eclipse-temurin:21-jre
+    image: eclipse-temurin:21.0.13_9-jre
     container_name: minecraft
     working_dir: /data
     command: java -Xmx4G -Xms2G -jar paper-1.21.11-54.jar nogui