Test against modern Node versions

Jest v29 pulls in pretty-format, which does not work with Node 12, as
shown in [this test run][1]:

      Run yarn install
      yarn install v1.22.21
      info No lockfile found.
      [1/4] Resolving packages...
      warning @grammarly/tslint-config > [email protected]: TSLint has been deprecated in favor of ESLint. Please see palantir/tslint#4534 for more information.
      warning jest-environment-jsdom > jsdom > [email protected]: Use your platform's native atob() and btoa() methods instead
      warning jest-environment-jsdom > jsdom > [email protected]: Use your platform's native DOMException instead
      warning jest-environment-jsdom > jsdom > data-urls > [email protected]: Use your platform's native atob() and btoa() methods instead
      warning [email protected]: Package no longer supported. Consider using eslint-plugin-sonarjs.
      [2/4] Fetching packages...
      error [email protected]: The engine "node" is incompatible with this module. Expected version "^14.15.0 || ^16.10.0 || >=18.0.0". Got "12.22.12"
      error Found incompatible module.

By testing against newer Node versions, we avoid this error.

Also, in general it's a good idea: Node 12 is no longer supported.
According to the chart on https://nodejs.org/en/about/previous-releases,
Node 16 is barely supported, and Node 18 and 20 are the stable versions.

[1]: https://github.com/grammarly/embrace/actions/runs/7065183069/job/19234690133?pr=11

Author: gabebw-grammarly

.github/workflows/tests.yml

@@ -9,7 +9,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [12.x]
+        node-version: [16.x, 18.x, 20.x]
 
     steps:
     - uses: actions/checkout@v4