dev: so tired of psych not building on various things

this time, it's the ruby:alpine images that removed all the -dev
libraries. JFC i'm just trying to stay green here.

Gemfile

@@ -33,8 +33,6 @@ end
 # If Psych doesn't build, you can disable this group locally by running
 # `bundle config set --local without rdoc`
 # Then re-run `bundle install`.
-unless RUBY_PLATFORM == "java" # see #3391 and https://github.com/jruby/jruby/issues/7262
-  group :rdoc do
-    gem "rdoc", "6.10.0"
-  end
+group :rdoc do
+  gem "rdoc", "6.10.0" unless RUBY_PLATFORM == "java" || ENV["CI"]
 end

scripts/test-gem-install

@@ -28,6 +28,7 @@ popd
 # 2.3.21 because https://github.com/rubygems/rubygems/issues/5914
 # 2.3.22 because https://github.com/rubygems/rubygems/issues/5940
 gem install bundler -v "~> 2.2, != 2.3.21, != 2.3.22"
+bundle config set --local without rdoc
 bundle install --local || bundle install
 
 rm -rf lib ext # ensure we don't use the local files