ci: pin psych until CI platforms have libyaml-dev

Author: flavorjones

sqlite3.gemspec

@@ -111,6 +111,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency("rake-compiler", "~> 1.2.0")
   s.add_development_dependency("rake-compiler-dock", "~> 1.2.1")
   s.add_development_dependency("rdoc", ">= 4.0", "< 7")
+  s.add_development_dependency("psych", "~> 4.0") # psych 5 doesn't build on some CI platforms yet
 
   s.extensions << "ext/sqlite3/extconf.rb"
 end