Update setup.cfg - update MIRA

[mwdchang]

Pin to the latest version of MIRA at time of writing.

[sabinala]

@djinnome I tried doing the same thing and got the same failing tests with error message for Test/build:

(X) Set up Python 3.8
-> Run actions/setup-python@v1
Error: Version 3.8 with arch x64 not found
Available versions:

3.10.1[5](https://github.com/ciemss/pyciemss/actions/runs/12374953908/job/34538659486?pr=636#step:5:6) (x64)
3.11.11 (x64)
3.12.8 (x64)
3.9.20 (x[6](https://github.com/ciemss/pyciemss/actions/runs/12374953908/job/34538659486?pr=636#step:5:7)4)

Does this mean something else in that config file needs to be updated? Should this line be changed to something like python_requires = >3.8?

[djinnome]

Superseded by #638