Use PMA_VERSION as build arg instead of env var

[ghost]

Hi @bunkerity ,

Hope you are all well !

Just noticed that PMA_VERSION should be rather used as a build arg rather than an environment variable: Ref. https://github.com/lucmichalski/bunkerized-phpmyadmin/blob/master/Dockerfile#L4

What do you think ? Any specific reason for using it as env var ?

Something like:

FROM bunkerity/bunkerized-nginx:${NGINX_VERSION:-"latest"}

ARG PMA_VERSION=${PMA_VERSION:-"5.0.4"}

# Download PHPMyAdmin sources
ENV PMA_VERSION ${PMA_VERSION}

Thanks for any insights or inputs about that question.

Cheers, Luc