docs: remove broken badge links

[nick-w-nick]

I noticed a handful of the badges at the top of the README have broken links and/or are unused. I thought I'd go ahead and submit a PR to remove them.

before:

after:

Thanks!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.81%. Comparing base (809227a) to head (b12e41a).
Report is 1 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (809227a) and HEAD (b12e41a). Click for more details.

HEAD has 4 uploads less than BASE

Flag	BASE (809227a)	HEAD (b12e41a)
	94	90

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1672      +/-   ##
==========================================
- Coverage   86.05%   78.81%   -7.24%     
==========================================
  Files          90       90              
  Lines        4877     4877              
  Branches      918      918              
==========================================
- Hits         4197     3844     -353     
- Misses        675      735      +60     
- Partials        5      298     +293     

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