Add react and react-dom as peerDependencies

[Oza94]

Installing this package via yarn 3 prints the following warnings :

➤ YN0002: │ @etchteam/storybook-addon-css-variables-theme@npm:1.2.1 doesn't provide react (paa6b6), requested by @storybook/api
➤ YN0002: │ @etchteam/storybook-addon-css-variables-theme@npm:1.2.1 doesn't provide react (p6e84a), requested by @storybook/theming
➤ YN0002: │ @etchteam/storybook-addon-css-variables-theme@npm:1.2.1 doesn't provide react (p3ee9d), requested by @storybook/addons
➤ YN0002: │ @etchteam/storybook-addon-css-variables-theme@npm:1.2.1 doesn't provide react (pb383a), requested by @storybook/components
➤ YN0002: │ @etchteam/storybook-addon-css-variables-theme@npm:1.2.1 doesn't provide react-dom (p15088), requested by @storybook/api
➤ YN0002: │ @etchteam/storybook-addon-css-variables-theme@npm:1.2.1 doesn't provide react-dom (p10d26), requested by @storybook/theming
➤ YN0002: │ @etchteam/storybook-addon-css-variables-theme@npm:1.2.1 doesn't provide react-dom (p7c3c4), requested by @storybook/addons
➤ YN0002: │ @etchteam/storybook-addon-css-variables-theme@npm:1.2.1 doesn't provide react-dom (pf64c0), requested by @storybook/components

Adding these lines to peerDependencies should do the trick :

    "react": "^16.8.0 || ^17.0.0 || ^18.0.0",
    "react-dom": "^16.8.0 || ^17.0.0 || ^18.0.0"

Would be happy to make a PR if needed

[gavmck]

Done!