feat: add support for direnv to second line

[patrickserrano]

Add support for displaying the current directory's Python virtual environment when direnv and pyenv are installed and being used.

[sjk07]

@patrickserrano cool! does this also work in sh?

also I don't use python but is this all the information that would be required for a user to understand what virtual env they are looking in and is there a better way to format the text?

ex (env-name python-version)

finally, could you add some description to the readme

[patrickserrano]

@sjk07 the name of the virtualenv shown in the prompt is name the user set when during virtualenv configuration + -<python version>. I think that's enough information to understand what they're looking at.

So in my screenshot the name of the virtualenv is virtual-env-test and it's using Python 3.6.5 which is how you get virtual-env-test-3.6.5. But when working on airflow the name that's displayed is airflow-3.6.5.

As for sh support, do the interactive features of prompt work with sh? I don't use it, but when I switched to sh and sourced the profile, it said I was using prompt but I only had a single line prompt with none of the features I'd get in bash or zsh. I also don't see in where in src/sh/profile we would be setting the prompt display.

Also, updated readme.

[sjk07]

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