Update node version to latest LTS

[lb-]

• Thought it would be good to be on the latest stable

[lb-]

Node 18 is now LTS - I have updated this PR to update to Node 18 instead of 16.

[lb-]

Looks like we are using a non-released version of docusaurus and the Node 18 update (with npm 7) could not resolve the packages, I have also added the npmrc config to use legacy peer deps for this sub-package.

https://docs.npmjs.com/cli/v7/using-npm/config#legacy-peer-deps

➜ npm install
npm ERR! code ERESOLVE
npm ERR! ERESOLVE could not resolve
npm ERR! 
npm ERR! While resolving: docusaurus-lunr-search@2.1.10
npm ERR! Found: react@17.0.1
npm ERR! node_modules/react
npm ERR!   react@"17.0.1" from the root project
npm ERR!   peer react@">= 16.8.0 < 18.0.0" from @docsearch/react@3.0.0-alpha.33
npm ERR!   node_modules/@docsearch/react
npm ERR!     @docsearch/react@"^3.0.0-alpha.33" from @docusaurus/theme-search-algolia@2.0.0-alpha.96e7fcef2
npm ERR!     node_modules/@docusaurus/theme-search-algolia
npm ERR!       @docusaurus/theme-search-algolia@"2.0.0-alpha.96e7fcef2" from @docusaurus/preset-classic@2.0.0-alpha.96e7fcef2
npm ERR!       node_modules/@docusaurus/preset-classic
npm ERR!         @docusaurus/preset-classic@"2.0.0-alpha.96e7fcef2" from the root project
npm ERR!   18 more (@docusaurus/core, @docusaurus/mdx-loader, ...)
npm ERR! 
npm ERR! Could not resolve dependency:
npm ERR! peer react@"^16.8.4" from docusaurus-lunr-search@2.1.10
npm ERR! node_modules/docusaurus-lunr-search
npm ERR!   docusaurus-lunr-search@"2.1.10" from the root project
npm ERR! 
npm ERR! Conflicting peer dependency: react@16.14.0
npm ERR! node_modules/react
npm ERR!   peer react@"^16.8.4" from docusaurus-lunr-search@2.1.10
npm ERR!   node_modules/docusaurus-lunr-search
npm ERR!     docusaurus-lunr-search@"2.1.10" 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 /.../.npm/eresolve-report.txt for a full report.

npm ERR! A complete log of this run can be found in:
npm ERR!     /...

[lb-]

not sure what to do here - code: 'ERR_OSSL_EVP_UNSUPPORTED' error with Netlify.