Move entry points from setup.py to setup.cfg

[douglatornell]

Supported by setuptools>=51.0.0 since 6-Dec-2020.

This is a step along the way of modernizing packaging.

[codecov]

Codecov Report

Merging #13 (a266935) into main (16ddb48) will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##             main      #13   +/-   ##
=======================================
  Coverage   95.14%   95.14%           
=======================================
  Files          11       11           
  Lines        1297     1297           
  Branches       88       88           
=======================================
  Hits         1234     1234           
  Misses         59       59           
  Partials        4        4           

Flag	Coverage Δ
unittests	95.14% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
setup.py	0.00% <0.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 16ddb48...a266935. Read the comment docs.

[douglatornell]

Testing on graham.

• Installation was fine
• salishsea run successfully prepared and queued a run

[douglatornell]

NEMO run and restart file rebuilding was successful.