Add Python (and other core dependency) support policy to our docs

[mfisher87]

IMO we should follow the Numpy policy and see how that works for us.

Follow up from discussion in #571

### Tasks
- [ ] Adopt a policy by consensus. Scientific Python SPEC0?
- [ ] Add Python support policy to docs (e.g. in "User Guide > Policies"?)
- [ ] Update project dependencies to follow new policy
- [ ] #471

[Sherwin-14]

@mfisher87 Hey, Is this the policy that you are talking about https://jax.readthedocs.io/en/latest/deprecation.html. If yes then how should we implement this in our context?

[jhkennedy]

Numpy's Python version support policy is: https://numpy.org/neps/nep-0029-deprecation_policy.html

Similarly, the scientific python policy is: https://scientific-python.org/specs/spec-0000/

[mfisher87]

I think we're not decided yet on what policy we want to use. I personally think Scientific Python SPEC0 (as referenced by @Sherwin-14 link above, and based on NEP29) is where we want to be.

• Support for Python versions be dropped 3 years after their initial release.
• Support for core package dependencies be dropped 2 years after their initial release.

This means we could drop support for Python 3.9 now :partying_face:

@jhkennedy beat me to it

EDIT: Moving cc to a new post to ensure notifications go out. No idea if edits can trigger notifications from @

[mfisher87]

@'ing some folks I think may have opinions :) @betolink @andypbarrett @JessicaS11 @chuckwondo @asteiker @danielfromearth

[mfisher87]

I added a task list to the original post of this ticket. I think if whoever takes this up wants to break off the piece about updating our deps to another ticket, please do :)

[mfisher87]

Fairly positive emoji responses to request for consensus on SPEC0, maybe we can decide on the hackathon call rq. :)

[Sherwin-14]

@mfisher87 Hey we have completed the 4th objective, what do you think about 2nd one? Do we need to create a Policies page or should we ignore this as it has already been mentioned in the backwards compatibility doc.

[mfisher87]

I think we can call that complete :) I wonder about number 3, are our dependencies already in compliance or do we need to make changes?

[mfisher87]

This was completed https://earthaccess.readthedocs.io/en/latest/user_guide/backwards-compatibility/#our-python-and-dependency-support-policy

#763