[ruby/English] Remove $IGNORECASE
$IGNORECASE
$= has been obsolete and has no effect since 1.9.
$=
https://github.com/ruby/English/commit/121939695a
[ruby/English] Remove
$IGNORECASE$=has been obsolete and has no effect since 1.9.https://github.com/ruby/English/commit/121939695a