Upgrade to Ember 4.8 and use Ember Octane syntax.

[dysonic]

This is my first time doing this so fingers crossed. The main changes are to upgrade to Ember 4.8 and use Ember Octane syntax. I couldn't get Ember try to work as it was getting errors:

ember try:one ember-lts-3.28 --- ember serve
Error!
Error: Cannot copy '../../../browserslist/cli.js' to a subdirectory of itself, '../../../browserslist/cli.js'.
Error: Cannot copy '../../../browserslist/cli.js' to a subdirectory of itself, '../../../browserslist/cli.js'.
    at /data/git/dysonic/ember-feature-flags/node_modules/ember-try/node_modules/fs-extra/lib/copy/copy.js:210:21
    at FSReqCallback.oncomplete (node:fs:188:23)

But I am assuming it should all be good. All the Ember tests passed. This is so the add on remains up to date, and to remove deprecation messages whilst using it.

[elgordino]

Just a note to say I am now using this commit in my project and it's working as expected. A note to anyone else trying, be sure to read the update in the README.

Thanks very much for putting this together. As a community user of this addon I would support this merge. Thanks.

[Baltazore]

Thanks for the work on it, I'll try to use it in my app from this branch