References to pantheon_solr8

I don't think anything is broken by this, but when searching my config files for instances of pantheon_solr8 to update them to pantheon_search, I noticed one in the module's source code.

search_api_pantheon/src/Services/SchemaPoster.php, line 265

public function getSolrFiles(string $server_id = 'pantheon_solr8') {

Obviously that's just a placeholder, as it seems to be working fine with the new ID passing to it, but just something to consider cleaning up.