handle expanded potential hash values
This extension suffers from the same problem as in https://github.com/civicrm/civicrm-core/pull/28354. This is the fix.
To quickly replicate, this works:
cv php:eval '$t = CRM_Sparkpost::getPartsFromBounceID("b.6897.8608748.8ywqcze3zuzvxl72@mysite.org"); var_export($t);'