Minor bug: dependency analysis not compatible with CFEP-25

[wshanks]

CFEP-25 suggests putting python {{ python_min }} in the host and test requirements sections (and probably only the host matters for this isssue), but the grayskull dependency analysis expects the specification to match the upstream package when it specifies a bound in requires-python. So when requires-python is >={{ python_min}}, the dependency analysis complains like this:

Packages found by grayskull but not in the meta.yaml:

python >=3.9

Packages found in the meta.yaml but not found by grayskull:

python 3.9

See for example conda-forge/abi3audit-feedstock#18. This is not a big deal, but it would be better not to complain here.