Fix default --version help message capitalisation.

[samhocevar]

The default help message for “--help” is capitalised, whereas the one
for “--version” was not:

-h,--help                   Print this help message and exit
-V,--version                display program version information and exit

[codecov]

Codecov Report

Merging #476 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #476   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           12        12           
  Lines         3724      3724           
=========================================
  Hits          3724      3724           

Impacted Files	Coverage Δ
include/CLI/App.hpp	100.00% <ø> (ø)

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[henryiii]

@all-contributors please add @samhocevar for code

[allcontributors]

@henryiii

I've put up a pull request to add @samhocevar! 🎉

[henryiii]

Thanks!