Chore: replace WebView with WKWebView

[sgsm74]

'WebView' was deprecated in macOS 10.14: No longer supported

[codecov-commenter]

Codecov Report

Patch and project coverage have no change.

Comparison is base (90ad768) 36.25% compared to head (5931883) 36.25%. Report is 2 commits behind head on master.

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Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1457   +/-   ##
=======================================
  Coverage   36.25%   36.25%           
=======================================
  Files         140      140           
  Lines       21644    21644           
=======================================
  Hits         7848     7848           
  Misses      13796    13796           

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[DavBfr]

It seems that's not enough.

[DavBfr]

I have a branch with WKWebView but it's incompatible with macOS < 11.0

[DavBfr]

https://github.com/DavBfr/dart_pdf/commit/d19639f39579ee3c4367926b19ad63a79a97ec9d