requirement file updates aren't detected

[gebhardtr]

Passing a requirements file to deps is really helpful; it would be great if updates to the requirements files were detected and a env recreate/install was triggered.

Version: 3.26.0

tox.ini

[testenv]
basepython = python3
install_command = pip3 install {opts} {packages}
deps = -r{toxinidir}/requirements-dev.txt

requirements-dev.txt

-r requirements.txt
pytest==6.2.5
...

Updating a dependency in requirements-dev.txt and requirements.txt doesn't trigger a recreate/reinstall, so old dependencies are used.

[gaborbernat]

Duplicate of #296