Support for Storybook 8

[alex1701c]

On startup with this plugin, one currently gets a warning and storybook exits with an error after:

WARN The following packages are incompatible with Storybook 8.0.4 as they depend on different major versions of Storybook packages:
WARN - storybook-addon-rem@1.3.0
WARN Repo: https://github.com/soelen/storybook-addon-rem#readme
WARN
WARN
WARN Please consider updating your packages or contacting the maintainers for compatibility details.
WARN For more on Storybook 8 compatibility, see the linked GitHub issue:
WARN storybookjs/storybook#26031

[alex1701c]

#5