Use awscli and boto3 extras only if required

[jakob-keller]

Description of Change

Use awscli and boto3 extras only if required:

• run CI without extras
• document local environment setup without extras

Assumptions

Replace this text with any assumptions made (if any)

Checklist for All Submissions

• I have added change info to CHANGES.rst
• If this is resolving an issue (needed so future developers can determine if change is still necessary and under what conditions) (can be provided via link to issue with these details):
  • Detailed description of issue
  • Alternative methods considered (if any)
  • How issue is being resolved
  • How issue can be reproduced
• If this is providing a new feature (can be provided via link to issue with these details):
  • Detailed description of new feature
  • Why needed
  • Alternatives methods considered (if any)

Checklist when updating botocore and/or aiohttp versions

• I have read and followed CONTRIBUTING.rst
• I have updated test_patches.py where/if appropriate (also check if no changes necessary)
• I have ensured that the awscli/boto3 versions match the updated botocore version

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.94%. Comparing base (24108bf) to head (6c51e79).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1250      +/-   ##
==========================================
- Coverage   88.16%   87.94%   -0.23%     
==========================================
  Files          67       67              
  Lines        5904     5904              
==========================================
- Hits         5205     5192      -13     
- Misses        699      712      +13     

Flag	Coverage Δ
unittests	87.94% <ø> (-0.23%)	⬇️

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