Add Makefile to export-ignore in .gitattributes (#56)

* Add Makefile to export-ignore in .gitattributes

* Update .gitattributes to export-ignore all phpstan configuration files

Author: roxblnfk

.gitattributes

@@ -2,5 +2,6 @@
 /examples export-ignore
 /tests export-ignore
 /.php-cs-fixer.dist.php export-ignore
-/phpstan.dist.neon export-ignore
+/phpstan* export-ignore
 /phpunit.xml.dist export-ignore
+/Makefile export-ignore