Regex captures aren't highlighted properly in double quoted strings

[samcv]

Issue Description

Compare the following:

Example Code

say "Nick [{$<nick>}] Units [{$<units>}] Time [{$<time>}] Message [{$<message>}]";
my $got = string-to-secs("$<time> $<units>");

[MadcapJake]

Ok I can get that fixed for sure. I actually want to make a full pass on variables inside of strings because there are other things not working as well.