chore: 恢复 dockerfile 写法，难以复用缓存但减小容器体积

Dockerfile

@@ -6,17 +6,16 @@ ENV LANG=zh_CN.UTF-8 \
     TZ=Asia/Shanghai \
     BILI_IN_DOCKER=true
 
+COPY poetry.lock pyproject.toml ./
+
 RUN apk add --no-cache ffmpeg tini \
     && apk add --no-cache --virtual .build-deps \
         gcc \
         musl-dev \
         libffi-dev \
         openssl-dev \
-    && pip install poetry
-
-COPY poetry.lock pyproject.toml ./
-
-RUN poetry config virtualenvs.create false \
+    && pip install poetry \
+    && poetry config virtualenvs.create false \
     && poetry install --only main --no-root \
     && apk del .build-deps \
     && rm -rf \