Support simple repository API v1.1 (PEP 700)

[EpicWink]

Get project versions and file sizes and upload-times from host indexes, and provide to clients. Set API version to 1.1 in project responses if valid (all files have size, and all indexes which host the project specify versions).

Issue: #15

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 96.07843% with 2 lines in your changes missing coverage. Please review.

Project coverage is 89.70%. Comparing base (cc219f4) to head (4579eb2).
Report is 14 commits behind head on master.

Files	Patch %	Lines
src/proxpi/_cache.py	95.45%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #43      +/-   ##
==========================================
+ Coverage   89.45%   89.70%   +0.25%     
==========================================
  Files           3        3              
  Lines         673      709      +36     
==========================================
+ Hits          602      636      +34     
- Misses         71       73       +2     

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[EpicWink]

TODO

• Testing