build: Remove nest-asyncio from core dependencies

[matthewfeickert]

• As the databinder module is deprecated and scheduled for removal (c.f. Find alternative to deprecated nest-asyncio dependency #355 (comment)), remove nest-asyncio from the required core dependencies.

$ git grep "nest_asyncio"  # Only used in databinder module
servicex/databinder/databinder_deliver.py:import nest_asyncio
servicex/databinder/databinder_deliver.py:nest_asyncio.apply()

• Add a 'databinder' extra that includes the nest-asyncio dependency, as the databinder module still exists and should be kept functional until it is removed or revised. (c.f. Find alternative to deprecated nest-asyncio dependency #355 (comment))

Amends PR #349.

[matthewfeickert]

cc @kyungeonchoi, @BenGalewsky, @gordonwatts for review.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.89%. Comparing base (4b8403c) to head (99dc757).

Additional details and impacted files

@@             Coverage Diff              @@
##           3.0_develop     #356   +/-   ##
============================================
  Coverage        79.89%   79.89%           
============================================
  Files               41       41           
  Lines             2253     2253           
============================================
  Hits              1800     1800           
  Misses             453      453           

Flag	Coverage Δ
unittests	79.89% <ø> (ø)

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[matthewfeickert]

👋 Ping for review.

[BenGalewsky]

Ah, this is nice.

[matthewfeickert]

Thanks for the review and merge, Ben!