[CI] Exclude PHPStan baseline from package exports

Author: Rafikooo

.gitattributes

@@ -9,6 +9,7 @@
 /Makefile export-ignore
 /phpspec.yml.dist export-ignore
 /phpstan.neon export-ignore
+/phpstan-baseline.neon export-ignore
 /phpunit.xml.dist export-ignore
 /psalm.xml export-ignore
 /rector.php