Fix support for params, data, and json as positional arguments to CachedSession.request()

[JWCook]

Fixes #524

[codecov-commenter]

Codecov Report

Merging #525 (db7444d) into master (aafc42f) will not change coverage.
The diff coverage is 100.00%.

❗ Current head db7444d differs from pull request most recent head fea0eff. Consider uploading reports for the commit fea0eff to get more accurate results

@@           Coverage Diff           @@
##           master     #525   +/-   ##
=======================================
  Coverage   98.61%   98.61%           
=======================================
  Files          18       18           
  Lines        1295     1295           
  Branches      188      188           
=======================================
  Hits         1277     1277           
  Misses          9        9           
  Partials        9        9           

Impacted Files	Coverage Δ
requests_cache/session.py	99.14% <100.00%> (ø)

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