update simple-cov for ruby 3.0 support

Author: hiraokashi

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
         # TODO: Wait for supporting Ruby 3.0 in simplecov-cobertura.
         # See https://github.com/dashingrocket/simplecov-cobertura/pull/16
         # ruby: [ 2.5, 2.6, 2.7, 3.0 ]
-        ruby: [ 2.6, 2.7, 3.0 ]
+        ruby: [ 3.0, 3.1, 3.2 ,3.3]
         exclude:
          - { os: macos-latest, ruby: '2.5' }
     runs-on: ${{ matrix.os }}

pb-serializer.gemspec

@@ -38,7 +38,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "rspec", "~> 3.0"
   spec.add_development_dependency "rubocop", "0.67.2" # for onkcop
   spec.add_development_dependency "sqlite3", "~> 1.4"
-  spec.add_development_dependency "simplecov", "~> 0.18.5"
-  spec.add_development_dependency "simplecov-cobertura", "~> 1.3"
+  spec.add_development_dependency "simplecov", "~> 0.19"
+  spec.add_development_dependency "simplecov-cobertura", "~> 2.0"
   spec.add_development_dependency "concurrent-ruby", "1.3.4"
 end