Can't parse one line end with CR

[ksss]

$ ruby -v
ruby 2.5.3p105 (2018-10-18 revision 65156) [x86_64-darwin16]

$ ruby -r csv -e 'puts CSV::VERSION'
3.0.0

CSV.parse("foo")
#=> [["foo"]]

CSV.parse("foo\n")
#=> [["foo"]]
CSV.parse("foo\nbar\n")
#=> [["foo"], ["bar"]]

CSV.parse("foo\r\n")
#=> [["foo"]]
CSV.parse("foo\r\nbar\r\n")
#=> [["foo"], ["bar"]]

CSV.parse("foo\r")
#=> CSV::MalformedCSVError (Unquoted fields do not allow \r or \n in line 1.)
CSV.parse("foo\rbar\r")
#=> [["foo"], ["bar"]]

Is it intentional?

I expect to be like this.

CSV.parse("foo\r")
#=> [["foo"]]

[kou]

It should be parsable.
I've added support for this case.