Update React to version 18

[MonkeyDo]

Related issue: #81

React 18 came out in March of this year.
Devs using react-bs-notifier and wishing to update to React 18 will see NPM errors about react-bs-notifier's peer dependency of react >=16.3 <18:

npm ERR! While resolving: react-bs-notifier@6.0.0
npm ERR! Found: react@18.2.0
npm ERR! node_modules/react
npm ERR!   react@"^18.2.0" from the root project
[…]
npm ERR! Could not resolve dependency:
npm ERR! peer react@">=16.3 <18" from react-bs-notifier@6.0.0
npm ERR! node_modules/react-bs-notifier
npm ERR!   react-bs-notifier@"^6.0.0" from the root project
npm ERR!
npm ERR! Conflicting peer dependency: react@17.0.2
npm ERR! node_modules/react
npm ERR!   peer react@">=16.3 <18" from react-bs-notifier@6.0.0
npm ERR!   node_modules/react-bs-notifier
npm ERR!     react-bs-notifier@"^6.0.0" from the root project

As far as I can tell no changes in the library code are required for this update to work (only changes are in the docs).
The two main options I see for this update are:

1. declare a peer dependency on react >=18 and publish a new major version of react-bs-notifier
2. modify the current peer dependency to react >=16.3 (removing <18) since no code change was required, and publish a new minor version of react-bs-notifier

I went for the first version, but I'm happy to modify the PR if option 2 is more appropriate.

Note on the updated package-lock.json file: the npm lockfile v2 format (used by npm v7) is backwards compatible to v1 lockfiles, so there shouldn't be any issues with the format change.

[chadly]

sorry for the late reply. I definitely appreciate this!

I will merge and release this evening.

[MonkeyDo]

Much obliged !