using string literal instead

Author: jhongturney

octocatalog-diff.gemspec

@@ -30,16 +30,16 @@ EOF
   s.add_runtime_dependency 'hashdiff', '>= 0.3.0'
   s.add_runtime_dependency 'parallel', '>= 1.12.0'
   s.add_runtime_dependency 'rugged', '>= 0.25.0b2'
-  if puppet_version == "4.10.10"
+  if puppet_version == '4.10.10'
     s.add_runtime_dependency 'puppet', '4.10.10'
     s.add_development_dependency 'puppet', '4.10.10'
-  elsif puppet_version == "5.5.22"
+  elsif puppet_version == '5.5.22'
     s.add_runtime_dependency 'puppet', '5.5.22'
     s.add_development_dependency 'puppet', '5.5.22'
-  elsif puppet_version == "6.18.0"
+  elsif puppet_version == '6.18.0'
     s.add_runtime_dependency 'puppet', '6.18.0'
     s.add_development_dependency 'puppet', '6.18.0'
-  elsif puppet_version == "7.3.0"
+  elsif puppet_version == '7.3.0'
     s.add_runtime_dependency 'puppet', '7.3.0'
     s.add_development_dependency 'puppet', '7.3.0'
   end