Remove sudo: false from travis config.

[vanniktech]

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

[codecov]

Codecov Report

Merging #36 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master      #36   +/-   ##
=========================================
  Coverage     67.08%   67.08%           
  Complexity       43       43           
=========================================
  Files             8        8           
  Lines           237      237           
  Branches         21       21           
=========================================
  Hits            159      159           
  Misses           66       66           
  Partials         12       12

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 67a6c02...9077672. Read the comment docs.