Fix dependencies

[jakob-keller]

Description of Change

Add missing runtime and dev dependencies.

Assumptions

All direct dependencies (i.e. used by codebase) should be specified as such.

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 88.07%. Comparing base (24108bf) to head (10a2fbd).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1246      +/-   ##
==========================================
- Coverage   88.16%   88.07%   -0.09%     
==========================================
  Files          67       67              
  Lines        5904     5904              
==========================================
- Hits         5205     5200       -5     
- Misses        699      704       +5     

Flag	Coverage Δ
unittests	88.07% <100.00%> (-0.09%)	⬇️

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[jakob-keller]

Maybe we should also update the Requirements section in README. Is that even necessary? It feels a bit redundant to me.