Allow childprocess 5 (sds#820)

I think it only brings improvements:
https://github.com/enkessler/childprocess/releases/tag/v5.0.0

Author: dentarg

overcommit.gemspec

@@ -27,7 +27,7 @@ Gem::Specification.new do |s|
 
   s.required_ruby_version = '>= 2.4'
 
-  s.add_dependency          'childprocess', '>= 0.6.3', '< 5'
+  s.add_dependency          'childprocess', '>= 0.6.3', '< 6'
   s.add_dependency          'iniparse', '~> 1.4'
   s.add_dependency          'rexml', '~> 3.2'
 end