upgrade alpine base image to v3.15.0 including openvpn package upgrade to v2.5.4-r0

https://github.com/OpenVPN/openvpn/blob/v2.5.2/ChangeLog
https://git.alpinelinux.org/aports/commit/main/openvpn?h=3.15-stable&id=b7e182e6f614394428fefe79875cb74cfe639205
https://git.alpinelinux.org/aports/commit/main/openvpn?h=3.15-stable&id=f3d3b2d920bafb894bdc14abfcc3b381685c8615
https://git.alpinelinux.org/aports/commit/main/openvpn?h=3.15-stable&id=ea84e4f989116e6b37a5744925e05a72a1cad013
https://git.alpinelinux.org/aports/commit/main/openvpn?h=3.15-stable&id=83010b93e55b081228c8c44da5d8f5e1fe50fe99

Dockerfile

@@ -1,6 +1,6 @@
-FROM alpine:3.14.3
+FROM docker.io/alpine:3.15.0
 
-ARG OPENVPN_PACKAGE_VERSION=2.5.2-r0
+ARG OPENVPN_PACKAGE_VERSION=2.5.4-r0
 RUN apk add --no-cache openvpn=$OPENVPN_PACKAGE_VERSION
 
 VOLUME /vpn-config

openvpn-package-log.url

@@ -0,0 +1 @@
+https://git.alpinelinux.org/aports/log/main/openvpn?h=3.15-stable