missing export-ignore for psalm-baseline.xml

Author: sasezaki

.gitattributes

@@ -13,7 +13,7 @@
 /phpunit.xml.dist export-ignore
 /psalm.xml export-ignore
 /psalm5.xml export-ignore
-/psalm-baseline.xml
+/psalm-baseline.xml export-ignore
 /mkdocs.yml export-ignore
 
 /example/ export-ignore