docker: update alpine image

Signed-off-by: László Várady <laszlo.varady@anno.io>

Author: MrAnno

docker/alpine.dockerfile

@@ -23,7 +23,7 @@
 
 ARG DEBUG=false
 
-FROM alpine:3.20 as apkbuilder
+FROM alpine:3.21 as apkbuilder
 
 ARG PKG_TYPE=stable
 ARG SNAPSHOT_VERSION
@@ -59,7 +59,7 @@ RUN mkdir packages \
     && abuild -r
 
 
-FROM alpine:3.20
+FROM alpine:3.21
 
 ARG DEBUG