fix appveyor build

[dapi]

No description provided.

[0crat]

@yegor256/z please, pay attention to this issue

[0crat]

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[yegor256]

@DronMDF can you please take a look?

[DronMDF]

@yegor256 Look at comment comment. Appveyor is missing a ruby.h. Maybe you can somehow fix the appveyor image?

[yegor256]

@DronMDF I have zero experience with Windows :( Maybe you can help?

[DronMDF]

@yegor256 I was wrong. ruby.h is present.

generating jaro_winkler_ext-x64-mingw32.def
mingw32-make: *** No rule to make target
'/C/Ruby25-x64/include/ruby-2.5.0/ruby.h', needed by 'adj_matrix.o'.  Stop.

File C:\Ruby25-x64\include\ruby-2.5.0\ruby.h exists.
What's wrong?

I'm not use WIndows too...
Need Windows ruby DEV for resolve this.

[yegor256]

@DronMDF this is what is happening now:

[DronMDF]

@yegor256 I see failure with ruby native extension.

Installing jaro_winkler 1.5.2 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

This is out of zold-score scope...
Need to fix build env..