Add phpunit.xml to composer

See phpmyadmin/sql-parser#125

Signed-off-by: Michal Čihař <michal@cihar.com>

Author: nijel

.gitattributes

@@ -3,5 +3,4 @@
 .gitignore export-ignore
 .travis.yml export-ignore
 codeconv.yml export-ignore
-phpunit.xml export-ignore
 .php_cs export-ignore