new deprecation warning from plugin update checker library in spro

[dhilditch]

No description provided.

Additional Context:
Replied to message: https://discord.com/channels/837258064704438282/857584095618007070/1448923045866504192

vakuya: Just wanted to let you know about these two depracation warnings on the plugin page.

[stephenfeather]

@dhilditch The 2 calls need a TypeHint for php 8+ as shown below

public function setUpdate(?Update $update = null): self {
    $this->lazyLoad();
    $this->update = $update;
    return $this;
}

The change is PHPCS / Psalm / PHPStan friendly

[dhilditch]

fixed in version 6.19