Bumps alpine from 3.13.3 to 3.13.4. Signed-off-by: dependabot[bot] <support@github.com>
@@ -1,4 +1,4 @@
-FROM docker.io/alpine:3.13.3
+FROM docker.io/alpine:3.13.4
ARG OPENSSH_SERVER_PACKAGE_VERSION=8.4_p1-r3
ENV SSHD_HOST_KEYS_DIR=/etc/ssh/host_keys