fix breaking specs in CI due to undefined method in ruby < 2.5

Author: Colby Swandale

lib/fileutils.rb

@@ -1274,8 +1274,15 @@ def door?
     def entries
       opts = {}
       opts[:encoding] = ::Encoding::UTF_8 if fu_windows?
-      Dir.children(path, opts)\
-          .map {|n| Entry_.new(prefix(), join(rel(), n.untaint)) }
+
+      files = if Dir.respond_to?(:children)
+        Dir.children(path, opts)
+      else
+        Dir.entries(path(), opts)
+           .reject {|n| n == '.' or n == '..' }
+      end
+
+      files.map {|n| Entry_.new(prefix(), join(rel(), n.untaint)) }
     end
 
     def stat