fix build error by upgrading to ruby3

(cherry picked from commit fdbe13d649e8a498eb87011a5d34820cfa0fe852)

rubygem-prawn.spec

@@ -2,7 +2,7 @@
 Summary:             A fast and nimble PDF generator for Ruby
 Name:                rubygem-%{gem_name}
 Version:             2.2.2
-Release:             1
+Release:             2
 License:             (GPLv2 or GPLv3 or Ruby) and APAFML
 URL:                 https://github.com/prawnpdf/prawn
 Source0:             http://rubygems.org/gems/prawn-%{version}.gem
@@ -63,7 +63,7 @@ sed -i "/^require 'bundler'/d" ./spec/spec_helper.rb
 sed -i "/^Bundler.setup/d" ./spec/spec_helper.rb
 rspec spec \
   | tee /dev/stderr \
-  | grep '850 examples, 103 failures'
+  | grep '850 examples, 106 failures'
 popd
 
 %files
@@ -88,5 +88,8 @@ popd
 %doc %{gem_instdir}/manual
 
 %changelog
+* Wed Feb 23 2022 chenchen <chen_aka_jan@163.com> - 2.2.2-2
+- fix build error by upgrading to ruby3
+
 * Tue Aug 4 2020 wangchong <wangchong56@huawei.com> - 2.2.2-1
 - package init