Bump version to 1.9.0

[henryiii]

No description provided.

[henryiii]

@phlptp, can you verify that I didn't miss anything obvious? Otherwise, I'll merge this and tag tomorrow.

[codecov]

Codecov Report

Merging #408 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #408   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          12     12           
  Lines        3580   3580           
=====================================
  Hits         3580   3580

Impacted Files	Coverage Δ
include/CLI/Validators.hpp	100% <ø> (ø)	⬆️

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[phlptp]

I didn't see much mention of the CMake changes in the changelog. I know those got rolled into another PR but I think they are worth a mention directly in the changelog as they were pretty significant.

Otherwise as far as I can tell everything look good.