fix: replace deprecated MAINTAINER with LABEL in Dockerfile (#84)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: vharseko <6818498+vharseko@users.noreply.github.com>

Author: Copilot

Dockerfile

@@ -1,6 +1,6 @@
 FROM eclipse-temurin:25-jre-jammy
 
-MAINTAINER Open Identity Platform Community <open-identity-platform-openidm@googlegroups.com>
+LABEL org.opencontainers.image.authors="Open Identity Platform Community <open-identity-platform-openidm@googlegroups.com>"
 
 ENV USER="openicf"
 ENV OPENICF_OPTS="-server -XX:+UseContainerSupport --add-exports java.base/com.sun.jndi.ldap=ALL-UNNAMED "