PHP 8.4: Implicitly marking parameters as nullable is deprecated

[jamieburchell]

Deployer Version

v7.4.0

Target OS

Rocky Linux 9

Which PHP version are you using?

PHP 8.3

Content of deploy.php or deploy.yaml

No response

Steps to reproduce

PHP 8.4 will produce deprecation errors:

Implicitly marking parameter $foo as nullable is deprecated, the explicit nullable type must be used instead.

[antonmedv]

We have to support old 7.3 for now. In next Deployer release we will bump min php to 8.

[jamieburchell]

Nullable types were introduced in 7.1, so that's not a problem

PHP supports nullable type declarations as of PHP 7.1 with the ?T syntax, and with the T|null syntax as of PHP 8.0 when generalized support for union types was added.

My PR fixes this.