Package does not work with Laravel 5.2, due to call to non-existant Request::userAgent() method

[DivineOmega]

Q	A
Bug?	yes
New Feature?	no
Framework	Laravel
Framework version	5.2
Package version	6.0.1
PHP version	7.1.15

Actual Behaviour

When the package attempts get the request's user agent it fails, as the Request object that is a part of Illuminate/Http 5.2 does not contain a userAgent method.

The error received is:

BadMethodCallException in Macroable.php line 74: Method userAgent does not exist.

    in Macroable.php line 74
    at Request->__call('userAgent', array()) in Facade.php line 215
    at Facade::__callStatic('userAgent', array()) in UserAgentResolver.php line 26
    at UserAgentResolver::resolve()
    at call_user_func(array('OwenIt\Auditing\Resolvers\UserAgentResolver', 'resolve')) in Auditable.php line 334

Expected Behaviour

User agent for the request is successfully retrieved, and audit is correctly logged.

Steps to Reproduce

Attempt to create/update/delete a model, while using v6.0.1 of the package in Laravel 5.2 will reproduce the problem.

Possible Solutions

In order to maintain compatibility with Laravel 5.2, the resolve() method in the UserAgentResolver class will need to be modified to not use the non-existant Request::userAgent() method.

An alternative is to just use Request::header('User-Agent').

[quetzyg]

Thanks for spotting this out, @DivineOmega.

It is in fact an issue with Laravel versions below 5.4.

[DivineOmega]

My pleasure.

[DivineOmega]

Is the PR sufficient?