Allow Redis::pconnect to have 7 parameters - #2695

This PR fixes a similar issue that was reported in phpstan/phpstan#9413 and subsequently fixed in #2442.

The Redis::pconnect method also accepts 7 parameters like the Redis::connect method, currently using all 7 available parameters on the pconnect method will show the error:

Method Redis::pconnect() invoked with 7 parameters, 1-5 required.

As can be seen here on the redis.stub.php the signature in the PHPStan function map is missing 2 parameters:

public function pconnect(string $host, int $port = 6379, float $timeout = 0, ?string $persistent_id = null, int $retry_interval = 0, float $read_timeout = 0, ?array $context = null): bool;

I've updated the function map to match the method signature.