Enable rubocop rule

.rubocop.yml

@@ -877,7 +877,7 @@ Lint/ParenthesesAsGroupedExpression:
                  Checks for method calls with a space before the opening
                  parenthesis.
   StyleGuide: 'https://github.com/bbatsov/ruby-style-guide#parens-no-spaces'
-  Enabled: false
+  Enabled: true
 
 Lint/RequireParentheses:
   Description: >-

lib/gitlab_custom_hook.rb

@@ -33,7 +33,7 @@ class GitlabCustomHook
 
     # we combine both stdout and stderr as we don't know what stream
     # will be used by the custom hook
-    Open3.popen2e (hook) do |stdin, stdout_stderr, wait_thr|
+    Open3.popen2e(hook) do |stdin, stdout_stderr, wait_thr|
       exit_status = true
       stdin.sync = true
 
@@ -43,7 +43,7 @@ class GitlabCustomHook
       begin
         # inject all the changes as stdin to the hook
         changes.lines do |line|
-          stdin.puts (line)
+          stdin.puts(line)
         end
       rescue Errno::EPIPE
       end

lib/gitlab_post_receive.rb

@@ -62,7 +62,7 @@ class GitlabPostReceive
 
       # Center the line by calculating the left padding measured in characters.
       line_padding = [(total_width - line.length) / 2, 0].max
-      puts (" " * line_padding) + line
+      puts(" " * line_padding) + line
     end
 
     puts