update submodule template to use current best practices

[knaaptime]

https://github.com/pysal/submodule_template

this should define our core infrastructure used across the packages, e.g.:

• requirements/environment files
• docs skeleton
• GHA recipes
• misc tooling shared across

[jGaboardi]

• Since we are now treating libpysal as the default "default" submodule template this can probably be closed.
• However, do we want to deprecate and remove the submodule_template?
  • use libpysal as the submodule_template submodule_template#46
  • use libpysal as the submodule_template libpysal#594
• Does this need a vote?

cc @martinfleis @sjsrey

[martinfleis]

Let's pick it up next time but I would probably archive it if it is not meant to be used.