ci: Dockerfile - 保留tzdata (#91)

* Dockerfile - keep tzdata for correct time

* Dockerfile - install tzdata only for correct logging time

refer to https://stackoverflow.com/a/68996528

Dockerfile

@@ -9,10 +9,7 @@ COPY ./*-bili-sync-rs ./targets/
 RUN apk update && apk add --no-cache \
     ca-certificates \
     tzdata \
-    ffmpeg \
-    && cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime \
-    && echo "Asia/Shanghai" > /etc/timezone \
-    && apk del tzdata
+    ffmpeg
 
 RUN if [ "$TARGETPLATFORM" = "linux/amd64" ]; then \
     mv ./targets/Linux-x86_64-bili-sync-rs ./bili-sync-rs; \