Add yubikey support

Dockerfile

@@ -3,7 +3,7 @@ FROM        alpine:"${ALPINE_VERSION}"
 
 LABEL       maintainer="https://github.com/hermsi1337"
 
-ARG         OPENSSH_VERSION="${OPENSSH_VERSION:-8.3_p1-r0}"
+ARG         OPENSSH_VERSION="${OPENSSH_VERSION:-8.3_p1-r2}"
 ENV         CONF_VOLUME="/conf.d"
 ENV         OPENSSH_VERSION="${OPENSSH_VERSION}" \
             CACHED_SSH_DIRECTORY="${CONF_VOLUME}/ssh" \
@@ -18,6 +18,8 @@ RUN         apk add --upgrade --no-cache \
                     bash-completion \
                     rsync \
                     openssh=${OPENSSH_VERSION} \
+                    openssh-server-pam \
+                    yubico-pam \
             && \
             mkdir -p /root/.ssh "${CONF_VOLUME}" "${AUTHORIZED_KEYS_VOLUME}" \
             && \