Docker: Alpine 3.21 (#7070)

PHP 8.3.14, Apache/2.4.62
https://alpinelinux.org/posts/Alpine-3.21.0-released.html

.devcontainer/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.20
+FROM alpine:3.21
 
 ENV TZ=UTC
 SHELL ["/bin/ash", "-eo", "pipefail", "-c"]

Docker/Dockerfile-Alpine

@@ -1,4 +1,4 @@
-FROM alpine:3.20
+FROM alpine:3.21
 
 ENV TZ=UTC
 SHELL ["/bin/ash", "-eo", "pipefail", "-c"]