MAINT: SPEC0

[jklenzing]

Description

Updates NEP29 testing config to SPEC0. Adds minimum versions of

• pandas
• scipy
• xarray

Minimum versions to be updated quarterly based on https://scientific-python.org/specs/spec-0000/

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

in pysat/pysat#1205

Checklist:

• Make sure you are merging into the develop (not main) branch
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have linted the files updated in this pull request
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• Add a note to CHANGELOG.md, summarizing the changes
• Update zenodo.json file for new code contributors

If this is a release PR, replace the first item of the above checklist with the
release checklist on the pysat wiki:
https://github.com/pysat/pysat/wiki/Checklist-for-Release