improved dockerfile

bot/dockerfile

@@ -1,12 +1,12 @@
-FROM alpine
+FROM alpine:3.7
 
 WORKDIR /app
 
-RUN apk add --no-cache git python3
-RUN git clone https://github.com/instabot-py/instabot.py.git .
-RUN python3 -m pip install --no-cache-dir -r requirements.txt
-RUN apk del --purge git
+COPY ./requirements.txt .
 
-COPY ./app.py .
+RUN apk add --no-cache python3
+RUN	python3 -m pip install --no-cache-dir -r requirements.txt
+
+COPY ./ .
 
 CMD [ "python3", "-u", "./app.py" ]