Not compatible with Sprockets 4

[johnnybenson]

See: https://github.com/rails/sprockets-rails/issues/269

Regular expressions are no longer supported in Sprockets.

https://github.com/decioferreira/bootstrap-generators/blob/master/lib/bootstrap-generators.rb#L14

-  app.config.assets.precompile << /\.(?:svg|eot|woff|woff2|ttf)$/
+  %w(eot svg ttf woff woff2).each do |ext|
+    app.config.assets.precompile << "bootstrap/glyphicons-halflings-regular.#{ext}"
+  end

This PR https://github.com/decioferreira/bootstrap-generators/pull/52 seems to work for:

Rails 5.2.4.1
ruby 2.5.5p157 (2019-03-15 revision 67260) [x86_64-darwin18]

[clarkewd]

I've also experienced this error. The PR seems good. +1 for merging.