Add Laravel 8 support

[Kussie]

Description of changes:
Adds support for Laravel 8

Changes:

• Bump supported version of Illuminate/support to ^8.0
• Bump the version of dotenv to include support for ^5.0
• Update docs to show support for Laravel 8

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[flemzord]

Laravel 8 is out :)

[Kussie]

All green and ready to go

[likeadeckofcards]

When will this be merged?

[j-fulbright]

+1

[huangdijia]

+1

[sidigi]

+1

[SamRemis]

This needs a changelog, once it is added, it shouldn't take long to merge

[Kussie]

@SamRemis This change is almost the same as the Laravel 7 support branch that was merged (Apart from version numbers). I can add the changes to the changelog.md if that is what you asking, but imho that should be done when a new version is tagged instead, which this is not doing. But regardless also added the exact changes made to the main comment, if you need something else to get this merged let me know and i will jump on it.

[duellsy]

@SamRemis Agree with @Kussie on this one, the CHANGELOG.md and the version number should only be bumped when the release is actually tagged, not as part of a PR, as it was with the 3.5.0 release: 7a37054

Are you able to handle this? It's holding up a lot of Laravel 8 upgrades :)

[duellsy]

Also tagging @howardlopez for input as they did the last couple of tagged releases 👋

[Cannonb4ll]

Waiting for this as well 👍

[martinduefrandsen]

When will this be merged?

[howardlopez]

Thanks fore the PR @Kussie!

[howardlopez]

Version 3.6.0 has been released with the changes. We appreciate your work on this @Kussie!