Remove sudo: false from travis config.

[vanniktech]

https://blog.travis-ci.com/2018-11-19-required-linux-infrastructure-migration

[codecov]

Codecov Report

Merging #162 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #162   +/-   ##
=========================================
  Coverage     54.43%   54.43%           
  Complexity       96       96           
=========================================
  Files             8        8           
  Lines           316      316           
  Branches         50       50           
=========================================
  Hits            172      172           
  Misses          132      132           
  Partials         12       12

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