Remove invalid multibyte char to avoid error in the deploy

There was a SyntaxError while loading apitome.gemspec:
/home/deploy/.gem/bundler/gems/apitome-96ab65a674c8/apitome.gemspec:13: invalid multibyte char (US-ASCII)
/home/deploy/.gem/bundler/gems/apitome-96ab65a674c8/apitome.gemspec:13: invalid multibyte char (US-ASCII)
/home/deploy/.gem/bundler/gems/apitome-96ab65a674c8/apitome.gemspec:13: syntax error, unexpected end-of-input, expecting keyword_end
... s.summary     = 'Apitome: /iˈpitəmē/ An API documentatio...
...                               ^