Allow refinerycms-core version from >= 3.0.0 to < 5.0

refinerycms-acts-as-indexed.gemspec

@@ -13,7 +13,7 @@ Gem::Specification.new do |s|
 
   s.files             = `git ls-files -- app/* lib/*`.split("\n")
 
-  s.add_dependency    'refinerycms-core', ['>= 3.0.0', '< 4.0']
+  s.add_dependency    'refinerycms-core', ['>= 3.0.0', '< 5.0']
   s.add_dependency    'acts_as_indexed', '~> 0.8.0'
   s.add_dependency    'decorators', '~> 2.0.0'
   s.add_dependency    'stringex', '~> 2.5.2'