fix(docker): install required deps

Dockerfile

@@ -6,11 +6,7 @@ LABEL repository="https://github.com/KevinNitroG/VNULIB-Downloader"
 
 WORKDIR /app
 
-RUN apk update
-RUN apk add libxml2 libxslt
-
 COPY requirements/requirements.txt /app/
-RUN pip install --no-cache-dir -r requirements.txt
 
 COPY assets/images/error_page.jpg /app/assets/images/
 COPY assets/utils/ascii_banner.txt /app/assets/utils/
@@ -19,7 +15,17 @@ COPY config-docker.yml /app/config.yml
 COPY main.py /app/
 COPY src/ /app/src/
 
-RUN apk add chromium
-RUN apk add chromium-chromedriver
+RUN apk update
+# https://gist.github.com/deliro/509b663093ff0f49c1b71e1876597ccb
+RUN apk add --no-cache --virtual .build-deps \
+      g++ \
+      python-dev \
+      libxml2 \
+      libxml2-dev && \
+    apk add libxslt-dev && \
+    pip install --no-cache-dir -r requirements.txt && \
+    apk del .build-deps
+
+RUN apk add --no-cache chromium chromium-chromedriver
 
 CMD ["python", "main.py"]