ci: use nodejs v18

[fossamagna]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Many pull requests to update dependencies is failed to build caused by Node.js version mismatch.

https://app.circleci.com/pipelines/github/nestjs/schematics/4206/workflows/cca4a55a-054e-48df-986f-5f23d177ac9c/jobs/8186

npm WARN config global `--global`, `--local` are deprecated. Use `--location=global` instead.
npm ERR! code EBADENGINE
npm ERR! engine Unsupported engine
npm ERR! engine Not compatible with your version of node/npm: npm@9.1.2
npm ERR! notsup Not compatible with your version of node/npm: npm@9.1.2
npm ERR! notsup Required: {"node":"^14.17.0 || ^16.13.0 || >=18.0.0"}
npm ERR! notsup Actual:   {"npm":"8.11.0","node":"v17.9.1"}

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/circleci/.npm/_logs/2022-11-17T20_08_00_907Z-debug-0.log


Exited with code exit status 1

Issue Number: N/A

What is the new behavior?

The build succeeds.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[kamilmysliwiec]

lgtm