Replaces raw dotenv load with dotenv_swtich.auto

[mberkowski]

Mainly, this is to load dotenv .env files via dotenv_switch.auto as in https://github.com/UMNLibraries/experts_etl/compare/dotenv-switch?expand=1#diff-2ef65ef8520cef01c37a957e90545296R1

Additionally:

• all dotenv_load() calls removed from individual etl modules, allowing it all to inherit from runner.py or tests/__init__.py
• Trailing whitespace auto-removed by .editorconfig

[mberkowski]

@nihiliad You should go ahead and merge this.

[nihiliad]

Working on it! Just updating some dotenv_switch dependency info on this branch first.