Update snakemake Python dependency

[wm75]

7.30.2 requires at least Python 3.9

I hope that's correct @johanneskoester?

[tsibley]

I concur with this PR. I noticed the issue when some of our CI with Python 3.8 + Snakemake 7.30.2 from Bioconda started failing with:

Traceback (most recent call last):
  File "…/bin/snakemake", line 6, in <module>
    from snakemake import main
  File "…/lib/python3.8/site-packages/snakemake/__init__.py", line 9, in <module>
    raise ValueError("Snakemake requires at least Python 3.9.")
ValueError: Snakemake requires at least Python 3.9.

when 7.30.2 should never have been selected by the solver for installation on 3.8 to begin with.

[tsibley]

@BiocondaBot please add label

[corneliusroemer]

Verified correctness of this PR, see
snakemake/snakemake#2341 (comment)
snakemake/snakemake#2370
snakemake/snakemake#2369

[corneliusroemer]

I don't know enough about build numbers to know whether Python 3.8 will now try to pick build 0 (before the version requirement bump was part of conda metadata).

[tsibley]

Indeed the solver (well, at least libmamba's solver) will just pick the build 0 instead. :-(

I thought it would, but tested anyway and was initially surprised because snakemake ==7.30.2 hdfd78af_1 (the build from this PR) got installed. Unfortunately it was able to be installed because it pulled in the pyhdfd78af_0 build of the snakemake-minimal package of the same version.

Can one yank releases/builds from Bioconda? I believe Anaconda's repositories let you do this, but who can do that for Bioconda?

Separately, it seems this pattern of the snakemake Conda package depending on the snakemake-minimal "sub" package should not only pin the exact same version as it does now but also the exact same build string. This doesn't functionally change the situation here, but it would likely help avoid other build mismatch issues in the future.

[tsibley]

Until someone can yank these files from Bioconda's channel:

snakemake-7.30.2-hdfd78af_0.tar.bz2
snakemake-minimal-7.30.2-pyhdfd78af_0.tar.bz2

then anyone with a Conda env with Python 3.7 or 3.8 trying to install Snakemake (without a version restriction) will get a broken version.

A workaround is to exclude 7.30.2, e.g.:

micromamba install 'snakemake !=7.30.2'

but this version restriction will be required in perpetuity (assuming Snakemake doesn't reintroduce support for 3.7 or 3.8).