Upgrade python3 Dockerfile for cassh-client

Author: Nicolas Béguier

src/client/Dockerfile

@@ -2,16 +2,16 @@ FROM alpine:latest
 
 # Container options (For layer optim)
 WORKDIR /app
-ENTRYPOINT ["python", "/app/cassh"]
+ENTRYPOINT ["python3", "/app/cassh"]
 CMD ["--help"]
 
 # Install dependencies
 RUN apk update \
     && apk add \
-        py2-pip
+        py3-pip
 
 COPY requirements.txt ./
 RUN pip install --no-cache-dir -r requirements.txt
 
 # Include code
-COPY cassh ./cassh
+COPY cassh ./cassh