signature_provided with " at the end

[KoljaL]

First: thank you for this function!

I orientated my code on the php-jwt-rest-authentication example, but i always got an invalid token.
After some research, i found out, that the $signature_provided always has a " at the end, but the $base64_url_signature not.

$base64_url_signature

MJrakX4rOoEf7dp9AU8aqcxd9oIsDbJWc15yVgwKe0M

$signature_provided

MJrakX4rOoEf7dp9AU8aqcxd9oIsDbJWc15yVgwKe0M"

Is this a known issue?