Log Message:
print/ruby-rbpdf: update to 1.21.0

1.21.0 (2023-02-13)

* Support for Ruby 3.0.0, 3.1.0, 3.2.0. (Drop support for Ruby 2.2 and
  earlier.) #66

* Support Rails 6 and Rails 7. (Drop support for Rails 3.x, 4.x) #66, #72

* Fix RMagick 5.0 compatible. #66

* Infinite loop has been resolved. #68, #74

* Fixed a bug that caused the x position to shift when an <img> tag was
  behind a <li> tag in HTML. #74

* fix: Incorrect characters when copying out of a generated PDF with Unicode
  fonts. #71

* Suppresses output for Circle(), Ellipse(), PieSector(), and PieSectorXY()
  when the radius is 0. #67

* Don't change an object while iterating over it #59 (by thegcat)

* fix : bidi bug #56 (by ahorek)

* Avoid rdoc stack level too deep (SystemStackError) in gem install. #76

* PDF example output option OUTPUT=true added #70

* Make the image file path acquisition process extensible #58 (by yui-har)