Fix curl_multi_exec deprecated functionality error

[edas11]

Describe the bug
When calling \Snowplow\Tracker\Tracker::flushEmitters we get a PHP Fatal error Deprecated Functionality: curl_multi_exec(): Passing null to parameter #2 ($still_running) of type int is deprecated in vendor/snowplow/snowplow-tracker/src/Emitters/CurlEmitter.php on line 173. We call flushEmitters in __destruct method of a custom class which sends some order data.

To Reproduce
Call \Snowplow\Tracker\Tracker::flushEmitters.

Expected behavior
No PHP Fatal errors.

Environment (please complete the following information):

• PHP 8.1
• Magento 2.4.5
• snowplow/snowplow-tracker 0.4.0. But it doesn't look like 0.5.0 has a fix for this.

[mscwilson]

Hi @edas11, really sorry that this issue got missed. We're looking into it now.

[mscwilson]

Hopefully this is fixed with version 0.6.1!