setExpires/getMaxAge: Notice: A non well formed numeric value encountered

[not-implemented]

Guzzle version(s) affected: 7.3.0
PHP version: 7.3.19-1~deb10u1
cURL version: 7.66.0

Description
The line $this->setExpires(\time() + $this->getMaxAge()); generates a "Notice: A non well formed numeric value encountered" when the received Cookie contains an invalid "Max-Age" for the cookie.

How to reproduce
In my case the server returned two comma separated values for Max-Age: "63071999,9843797"

Possible Solution
Either explicitly cast the return value from $this->getMaxAge() to "int", or add an additional validation for "digits only".