feat: support start the container as non-root user (close #45, close #47)

Dockerfile

@@ -7,6 +7,8 @@ LABEL "repository"="https://github.com/ttionya/vaultwarden-backup" \
 COPY scripts/*.sh /app/
 
 RUN chmod +x /app/*.sh \
-  && apk add --no-cache bash sqlite p7zip heirloom-mailx tzdata
+  && apk add --no-cache bash heirloom-mailx p7zip sqlite supercronic tzdata \
+  && ln -sf /tmp/localtime /etc/localtime \
+  && mkdir -m 777 /bitwarden
 
 ENTRYPOINT ["/app/entrypoint.sh"]