Update dependency of react to 18

Right now, an application using react 18.0.0 using react-countdown-clock only works with npm install --legacy-peer-deps, otherwise it fails with the following error:

$ npm install
npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR! 
npm ERR! While resolving: react-quiz@0.2.0
npm ERR! Found: react@18.0.0
npm ERR! node_modules/react
npm ERR!   react@"^18.0.0" from the root project
npm ERR! 
npm ERR! Could not resolve dependency:
npm ERR! peer react@"^17.0.2" from react-countdown-clock@2.9.0
npm ERR! node_modules/react-countdown-clock
npm ERR!   react-countdown-clock@"^2.9.0" from the root project
npm ERR! 
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.
npm ERR! 
npm ERR! See /home/konrad/.npm/eresolve-report.txt for a full report.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/konrad/.npm/_logs/2022-04-13T13_10_20_573Z-debug-0.log

However it seems to work fine with React 18, so I think it can safely be changed.

pughpugh / react-countdown-clock

Update dependency of react to 18 #76