R1:23a3f59be227

Fix typo creating QRbitstream()

Summary:
Make the one `new QRbitrtream()` look like the other nine `new QRbitstream()`.

Interestingly, this bug was reported upstream since 2018, and still not fixed:

https://github.com/t0k4rt/phpqrcode/issues/47

Test Plan:
Read the code aloud and realize that this word sound weird.

Verify that the class `QRbitrtream` does not exist, and `QRbitstream` exists.

Reviewers: O1 Blessed Committers, valerio.bozzolan

Reviewed By: O1 Blessed Committers, valerio.bozzolan…