update Dockerfile

Dockerfile

@@ -1,10 +1,7 @@
-FROM ubuntu
-ENV TZ=Etc/UTC
-RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
-RUN apt-get update && apt-get install --yes pkg-config libsystemd-dev
-RUN add-apt-repository ppa:deadsnakes/ppa -y
-RUN apt-get update
-RUN apt install python3.7
+FROM python:3.7.15
+
+RUN apt-get update && \
+    apt-get install -y git pkg-config libsystemd-dev
 
 # Set the working directory in the container to /app
 WORKDIR /app