Dockerfile update

Dockerfile

@@ -1,25 +1,16 @@
-FROM python:3.7
-LABEL maintainer="Soxoj <soxoj@protonmail.com>"
-
+FROM python:3.9
+MAINTAINER Soxoj <soxoj@protonmail.com>
 WORKDIR /app
-
-ADD requirements.txt .
-
 RUN pip install --upgrade pip
-
-RUN apt update -y
-
-RUN apt install -y\
+RUN apt update && \
+	apt install -y \
       gcc \
       musl-dev \
       libxml2 \
       libxml2-dev \
-      libxslt-dev \
-&&  YARL_NO_EXTENSIONS=1 python3 -m pip install maigret \
-&&  rm -rf /var/cache/apk/* \
-           /tmp/* \
-           /var/tmp/*
-
+      libxslt-dev
+RUN apt clean \
+    && rm -rf /var/lib/apt/lists/* /tmp/*
 ADD . .
-
+RUN YARL_NO_EXTENSIONS=1 python3 -m pip install .
 ENTRYPOINT ["maigret"]