Python version too old

[CarlosTejeiro]

Tested with T-Rex v2.56 and v3.03

`
C9300E#app-hosting start appid trex
trex started successfully
Current state is: RUNNING
C9300E#app-hosting connect appid trex session

./t-rex-64 -i --cfg /iox_data/appdata/trex_cfg_cat9k.yaml

*** Python3 version is too old, 3.4 or later is required
ERROR encountered while configuring TRex system
`

[CarlosTejeiro]

I've fixed editing the dockerfile:

FROM ubuntu:16.04

RUN apt-get update && \
    apt-get -y install python3 \
                       python3-pip \
                       wget \
                       bash \
                       net-tools \
                       netbase \
                       strace \
                       iproute2 \
                       iputils-ping \
                       pciutils \
                       vim
RUN wget https://trex-tgn.cisco.com/trex/release/v2.56.tar.gz --no-check-certificate && \
    tar -zxvf v2.56.tar.gz -C / && \
    chown root:root /v2.56 && \
    rm v2.56.tar.gz
COPY trex_cfg_cat9k.yaml /etc/trex_cfg_cat9k.yaml

WORKDIR /v2.56

CMD ["./t-rex-64", "-i", "--cfg", "/etc/trex_cfg_cat9k.yaml"]