Drop IE11 and Safari 9 from Sauce Labs test runners

[fatso83]

Purpose (TL;DR) - mandatory

• Drop IE11 and Safari 9 per discussion in Retry - Add stack trace to code recursively scheduling timers #325  #375 and Official Sinon docs are erroneous with regards to browser support sinon#2359.
• Also copies in browsers from the mother Sinon repo to include Edge and Safari latest

Background (Problem in detail) - optional

See discussion in #375 and sinonjs/sinon#2359

[codecov]

Codecov Report

Merging #376 (3e07631) into master (07d90ce) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #376   +/-   ##
=======================================
  Coverage   93.49%   93.49%           
=======================================
  Files           1        1           
  Lines         553      553           
=======================================
  Hits          517      517           
  Misses         36       36           

Flag	Coverage Δ
unit	93.49% <ø> (ø)

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[benjamingr]

Should we do a version that modernizes the codebase? (I'm happy to run the code through transforms that modernize it if we don't need to support IE11)

[fatso83]

I would not mind that. The only problem I have with large touch-everything stuff like running Prettier, Eslint and transforms on the code is that it makes git blame a lot less useful, but I can live with that.