Following the advice of rubygems:

WARNING:  pessimistic dependency on refinerycms-core (~> 3.0.0) may be overly strict
  if refinerycms-core is semantically versioned, use:
    add_runtime_dependency 'refinerycms-core', '~> 3.0', '>= 3.0.0'
WARNING:  pessimistic dependency on friendly_id (~> 5.0.1) may be overly strict
  if friendly_id is semantically versioned, use:
    add_runtime_dependency 'friendly_id', '~> 5.0', '>= 5.0.1'
WARNING:  See http://guides.rubygems.org/specification-reference/ for help

refinerycms-settings.gemspec

@@ -15,6 +15,6 @@ Gem::Specification.new do |s|
   s.files             = `git ls-files`.split("\n")
   s.test_files        = `git ls-files -- spec/*`.split("\n")
 
-  s.add_dependency    'refinerycms-core',     '~> 3.0.0'
-  s.add_dependency    'friendly_id',          '~> 5.0.1'
+  s.add_dependency    'refinerycms-core',     ['~> 3.0', '>= 3.0.0']
+  s.add_dependency    'friendly_id',          ['~> 5.0', '>= 5.0.1']
 end