Stop bundling configobj

[WilliamJamieson]

Currently stpipe bundles its own copy of configobj; however, astropy also bundles a copy of configobj. The only major differences between the stpipe version and the astropy version are the changes from #108 (this was recently fixed by astropy) and some errant conversions of strings to f-strings via applications of automated tools. Since astropy is a required dependency of stpipe, we might as well just use the configobj maintained and bundled directly by astropy rather than further duplicating it.

[codecov]

Codecov Report

Attention: 68 lines in your changes are missing coverage. Please review.

Files	Coverage Δ
src/stpipe/cli/command.py	100.00% <ø> (+27.27%)	⬆️
src/stpipe/cli/list.py	97.29% <100.00%> (ø)
src/stpipe/cli/main.py	87.17% <100.00%> (ø)
src/stpipe/datamodel.py	100.00% <100.00%> (+11.11%)	⬆️
src/stpipe/exceptions.py	62.50% <100.00%> (-4.17%)	⬇️
src/stpipe/format_template.py	97.61% <100.00%> (-0.06%)	⬇️
src/stpipe/entry_points.py	50.00% <0.00%> (+2.63%)	⬆️
src/stpipe/utilities.py	76.59% <75.00%> (-0.49%)	⬇️
src/stpipe/config.py	58.53% <0.00%> (ø)
src/stpipe/crds_client.py	35.13% <0.00%> (+1.80%)	⬆️
... and 8 more

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[WilliamJamieson]

This passes the regression tests:

• https://plwishmaster.stsci.edu:8081/job/RT/job/Roman-Developers-Pull-Requests/447/ (failure is known and unrelated)
• https://plwishmaster.stsci.edu:8081/job/RT/job/JWST-Developers-Pull-Requests/1018/

[perrygreenfield]

LGTM and well worth doing.