Add export-ignore attribute for .laminas-ci.json

The file was already listed in `.gitattributes` since
5605861, but without any actual attributes
which I assume to be an oversight.

Signed-off-by: Tim Düsterhus <duesterhus@woltlab.com>

.gitattributes

@@ -2,7 +2,7 @@
 /.gitattributes export-ignore
 /.github/ export-ignore
 /.gitignore export-ignore
-/.laminas-ci.json
+/.laminas-ci.json export-ignore
 /docs/ export-ignore
 /mkdocs.yml export-ignore
 /phpcs.xml export-ignore