requirements.txtwas associated with binder in ec7beaa,
which I think is wrong, because requirements.txt is primary used for installing packages from pypi:
https://pip.pypa.io/en/latest/user_guide/#requirements-files

There is already a definition for requirements.in:

which points to pypi, which should be extended to apply also for other requirements file names.

I have seen the following requirements file names:

• requirements-dev.txt
• requirements-doc.txt
• requirements_docs.txt
• requirements-test.txt
• requirements_test.txt

So maybe the match can be adjusted to also catch these file names. Something like:
/^(dev-)?requirements.*\.(in|txt)$/