Retirement of Ruby 2.7

[Takahiro Kambe <taca%NetBSD.org@localhost>]

Hi,

Ruby 2.7 is already EOL and it should be removed from pkgsrc before
next pkgsrc branch cutting.

Current packages supported by Ruby 2.7 are:

	devel/ruby-redmine42
	math/ruby-gsl		(no activity after 2021-09-07)
	textproc/ruby-oniguruma	(no repository?)
	x11/ruby-wxruby		(no repository?)

I'll remove them and some related supporting pacakges before this
month is out.

Best regards.

-- 
Takahiro Kambe <taca%NetBSD.org@localhost>