Make library compatible with php 8

[webmake]

These errors occurs:
TypeError: Unsupported operand types: string - int
/vendor/jukylin/jaeger-php/src/Jaeger/Transport/TransportUdp.php:62

Deprecated: Required parameter $reporter follows optional parameter $serverName in /vendor/jukylin/jaeger-php/src/Jaeger/Jaeger.php on line 51