chore: remove ie 11 support

[kchang-brightcove]

Removed IE 11 support

[misteroneill]

It looks like this is still running tests against Safari 9 and failing because it doesn't recognize const. We should change the browsers it runs tests against.

[codecov]

Codecov Report

Merging #160 (6486202) into main (cd75be1) will increase coverage by 0.12%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #160      +/-   ##
==========================================
+ Coverage   94.34%   94.46%   +0.12%     
==========================================
  Files          19       19              
  Lines         778      795      +17     
  Branches      242      241       -1     
==========================================
+ Hits          734      751      +17     
  Misses         44       44              

Impacted Files	Coverage Δ
src/utils/list.js	100.00% <ø> (ø)
src/playlist-merge.js	98.07% <100.00%> (+0.03%)	⬆️
src/toM3u8.js	98.76% <100.00%> (+0.01%)	⬆️
src/parseAttributes.js	100.00% <0.00%> (ø)
src/segment/durationTimeParser.js	95.83% <0.00%> (+0.18%)	⬆️

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