Do not copy file which was removed in 2.6

See 479c83f71847af81c96a2d51e375b7a5f6797c4c in MRI.

Author: eregon

tool/import-mri-files.sh

@@ -41,7 +41,6 @@ cp -r ../ruby/ext/openssl/lib/* lib/mri
 
 cp ../ruby/ext/psych/*.{c,h,rb} src/main/c/psych
 cp ../ruby/ext/psych/yaml/*.{c,h} src/main/c/psych/yaml
-cp ../ruby/ext/psych/yaml/LICENSE src/main/c/psych/yaml
 cp ../ruby/ext/psych/lib/psych.rb lib/mri
 cp -r ../ruby/ext/psych/lib/psych lib/mri