Make dependency to rexml

[toshia]

ruby-dbus make crash on load in ruby 3.0.0 .

/home/toshi/Project/mikutter/vendor/bundle/mikutter-cli/ruby/3.0.0/gems/ruby-dbus-0.16.0/lib/dbus/xml.rb:13:in `require': cannot load such file -- rexml/document (LoadError)
        from /home/toshi/Project/mikutter/vendor/bundle/mikutter-cli/ruby/3.0.0/gems/ruby-dbus-0.16.0/lib/dbus/xml.rb:13:in `<top (required)>'

In ruby 3, rexml becomes bundled gem.
I think ruby-dbus should make dependency to 'rexml'.

see: rails/rails#40281

[coveralls]

Coverage increased (+0.08%) to 88.311% when pulling 6103894 on toshia:add-dependency-rexml into b61c2c4 on mvidner:master.

[voxik]

Actually, I wonder if it was not better to drop the REXML dependency altogether given that Nokogiri have been already supported:

ruby-dbus/lib/dbus/xml.rb

Lines 95 to 99 in b61c2c4

	@backend = if AbstractXML.have_nokogiri?
	NokogiriParser
	else
	REXMLParser
	end

[na-sa-do]

@mvidner Please consider this PR. The gem is currently unusable on Ruby 3.

[felipec]

Actually, I wonder if it was not better to drop the REXML dependency altogether given that Nokogiri have been already supported:

Nokogiri would also be another dependency.

There's no need burden this request with other potential changes.

Just add the rexml dependency now, and consider moving to nokogiri later.

[mvidner]

Actually, I wonder if it was not better to drop the REXML dependency altogether given that Nokogiri have been already supported

Comparing the gem sizes gives me a reason to not make nokogiri mandatory:

rexml: 3.2.5 - April 05, 2021 (91 KB)
nokogiri: 1.13.1 - January 13, 2022 (9.15 MB)

[mvidner]

Thank you!