only tidy perl files

.gitignore

@@ -5,3 +5,4 @@ lab
 .envrc
 *.orig
 *.tdy
+*.ERR

xt/perltidy.t

@@ -17,7 +17,9 @@ if ($on_target) {
 else {
     my @files =
       $git->diff( { name_only => 1, diff_filter => 'ACMR' }, $target_branch );
-    ok Test::PerlTidy::is_file_tidy($_), $_ for @files;
+    ok Test::PerlTidy::is_file_tidy($_), $_
+      for grep { /\.(pl|pm|pod|t)$/ } @files;
+
 }
 
 done_testing;