Review `cebe\yii2openapi\lib\openapi\PropertySchema::getRefSchemaName()`

File: src/lib/openapi/PropertySchema.php

```php
public function getRefSchemaName():string
{
    ...
    $separateFilePattern = '/((\.\/)*)(?<schemaName>.+)(\.)(yml|yaml)(.*)/'; # https://github.com/php-openapi/yii2-openapi/issues/74 
    # TODO `(yml|yaml|json)` ?
```