SQLFluff: Recursive Stack Overflow in Parser

### Impact In deployments where untrusted users can provide SQL queries to be linted, an untrusted user can submit a malicious query with deliberate excessive nesting to any application using the parser to trigger a Denial of Service through resource exhaustion. ### Patches Versions 4.1.0 and up contain a configurable recursion limit, which is enabled by default, to prevent this manner of exploit. ### Credit Ori Nakar from Imperva Threat Research Team.