Update Dockerfile for faster build

Dockerfile

@@ -1,20 +1,23 @@
 FROM python:3.8-slim
 
-ENV PYTHONFAULTHANDLER=1
-ENV PYTHONUNBUFFERED=1
-ENV PYTHONHASHSEED=random
-ENV PYTHONDONTWRITEBYTECODE 1
-ENV PIP_NO_CACHE_DIR=off
-ENV PIP_DISABLE_PIP_VERSION_CHECK=on
-ENV PIP_DEFAULT_TIMEOUT=100
+RUN \
+    set -eux; \
+    apt-get update; \
+    DEBIAN_FRONTEND="noninteractive" apt-get install -y --no-install-recommends \
+    python3-pip \
+    build-essential \
+    python3-venv \
+    ffmpeg \
+    git \
+    ; \
+    rm -rf /var/lib/apt/lists/*
 
-RUN apt-get update
-RUN apt-get install -y python3 python3-pip python3-dev build-essential python3-venv ffmpeg
+RUN pip3 install -U pip && pip3 install -U wheel && pip3 install -U setuptools==59.5.0
+COPY ./requirements.txt /tmp/requirements.txt
+RUN pip3 install -r /tmp/requirements.txt && rm -r /tmp/requirements.txt
 
-RUN mkdir -p /code
-ADD . /code
+COPY . /code
 WORKDIR /code
 
-RUN pip3 install -r requirements.txt
-
 CMD ["bash"]
+