Use Regexp#match? when MatchData is not required

[ashmaroli]

• This is a 🔨 code refactoring.

Summary

Regexp#match? is the faster alternative from Ruby 2.4 when the MatchData object is not consequently utilized.

While the first build after running jekyll clean won't have files in the dest-dir, consequent builds will have the directory populated. So this line could get executed numerous times especially in a site with numerous pages and files

[DirtyF]

All green, jekyll site seems to compile a little bit faster, memory allocation is still mostly Kramdown and Nokogiri.

[ashmaroli]

memory allocation is still mostly kramdown and nogikiri

Allocations from Nokogiri will reduce when they release v1.11.0..

[ashmaroli]

@jekyllbot: merge +fix