UID2-7335: bump eclipse-temurin base to sha256:3f08b138 (ships libexpat 2.8.1-r0)

The 2026-06-22 rebuild of 21-jre-alpine-3.23 (sha256:3f08b138) now ships
libexpat 2.8.1-r0, so the explicit 'apk add --upgrade libexpat' added in the
previous fix (CVE-2026-45186) is no longer needed and is removed, matching the
repo convention of dropping per-package upgrades once the base carries the fix.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: swibi-ttd

Dockerfile

@@ -1,5 +1,5 @@
-# sha from https://hub.docker.com/layers/library/eclipse-temurin/21-jre-alpine-3.23/images/sha256-693c22ea458d62395bac47a2da405d0d18c77b205211ceec4846a550a37684b6
-FROM eclipse-temurin@sha256:693c22ea458d62395bac47a2da405d0d18c77b205211ceec4846a550a37684b6
+# sha from https://hub.docker.com/layers/library/eclipse-temurin/21-jre-alpine-3.23/images/sha256-3f08b13888f595cc49edabea7250ba69499ba25602b267da591720769400e08c
+FROM eclipse-temurin@sha256:3f08b13888f595cc49edabea7250ba69499ba25602b267da591720769400e08c
 
 WORKDIR /app
 EXPOSE 8089
@@ -17,7 +17,7 @@ COPY ./conf/default-config.json /app/conf/
 COPY ./conf/*.xml /app/conf/
 COPY ./webroot/ /app/webroot/
 
-RUN apk add --no-cache --upgrade libpng libcrypto3 libssl3 musl musl-utils gnutls libexpat && adduser -D uid2-admin && mkdir -p /app && chmod 705 -R /app && mkdir -p /app/file-uploads && chmod 777 -R /app/file-uploads
+RUN apk add --no-cache --upgrade libpng libcrypto3 libssl3 musl musl-utils gnutls && adduser -D uid2-admin && mkdir -p /app && chmod 705 -R /app && mkdir -p /app/file-uploads && chmod 777 -R /app/file-uploads
 USER uid2-admin
 
 CMD java \