Improve ci

[o0h]

I believe this pr would make the plugin more sustainable 💪

• Check if run on min-ver. cakephp(3.5) in addition to current config as latest-ver only(3.8.x now).
• Check if run on PHP in early build(7.4)
• Generate code coverage with phpdbg alter to xdebug
  • see: https://docs.travis-ci.com/user/speeding-up-the-build/#php-optimizations

[codecov-io]

Codecov Report

Merging #23 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             master    #23   +/-   ##
=======================================
  Coverage       100%   100%           
  Complexity       35     35           
=======================================
  Files             2      2           
  Lines           129    129           
=======================================
  Hits            129    129

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[itosho]

@o0h LGTM! Thank you for your kindness!!