Fix dependencies, using vanilla responder package from PyPI, version 2

[amotl]

What the title says.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.12%. Comparing base (50e531b) to head (02e40d3).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #28      +/-   ##
==========================================
- Coverage   69.26%   69.12%   -0.15%     
==========================================
  Files          12       12              
  Lines         218      217       -1     
==========================================
- Hits          151      150       -1     
  Misses         67       67              

Flag	Coverage Δ
unittests	69.12% <ø> (-0.15%)	⬇️

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[amotl]

Coming from kennethreitz/responder#522, we discovered a potential successor project to Responder: Dyne is a fork of Responder with batteries included, self-documenting OpenAPI endpoints, focused on extensibility, simplicity, usability, and elegance.