Fix Travis CI error

[ken-matsui]

No description provided.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (develop@54d0891). Click here to learn what that means.
The diff coverage is 100%.

@@            Coverage Diff             @@
##             develop     #166   +/-   ##
==========================================
  Coverage           ?   66.34%           
==========================================
  Files              ?       97           
  Lines              ?     5410           
  Branches           ?        0           
==========================================
  Hits               ?     3589           
  Misses             ?     1821           
  Partials           ?        0

Impacted Files	Coverage Δ
include/poac/io/term.hpp	43.28% <ø> (ø)
include/poac/opts/update.hpp	11.32% <100%> (ø)

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