upgrade alpine base image v3.12.2->3.12.3 including openssh-server package upgrade v8.3_p1-r0->v8.3_p1-r1 (patch for CVE-2020-14145 in openssh-client, irrelevant for server)

> The client side in OpenSSH 5.7 through 8.3 has an Observable Discrepancy leading to an information leak in the algorithm negotiation. This allows man-in-the-middle attackers to target initial connection attempts (where no host key for the server has been cached by the client).

https://git.alpinelinux.org/aports/commit/?id=20ed8327b9ee7b0920813b009bcbd8001f07a3b5

Dockerfile

@@ -1,6 +1,6 @@
-FROM alpine:3.12.2
+FROM alpine:3.12.3
 
-ARG OPENSSH_SERVER_PACKAGE_VERSION=8.3_p1-r0
+ARG OPENSSH_SERVER_PACKAGE_VERSION=8.3_p1-r1
 RUN apk add --no-cache openssh-server=$OPENSSH_SERVER_PACKAGE_VERSION
 
 ENV SSHD_HOST_KEYS_DIR /etc/ssh/host_keys