Relax Node.js version to ^14.20.1 and bump .nvmrc to v14.21.3

* `engines.node` is relaxed from `14.20.1` to `^14.20.1`: yarn and OSD will allow versions 14.20.1 or greater, but less than 15, to be used but do not impose upgrading to avoid being a breaking change. Users will be able to install any version of Node.js that satisfies `^14.20.1`, moving ahead without waiting for a change in OSD when new versions are released.
* `.nvmrc` is bumped to the latest security patch: `14.21.3`

Signed-off-by: Miki <miki@amazon.com>

.node-version

@@ -1 +1 @@
-14.20.1
+14.21.3

.nvmrc

@@ -1 +1 @@
-14.20.1
+14.21.3

CHANGELOG.md

@@ -134,6 +134,8 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Bumps `re2` and `supertest` ([3018](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3018))
 - Bump `vega-tooltip` version from ^0.24.2 to ^0.30.0 ([#3358](https://github.com/opensearch-project/OpenSearch-Dashboards/issues/3358))
 - Allow relaxing the Node.js runtime version requirement ([3402](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3402))
+- Relax the Node.js requirement to `^14.20.1` ([3463](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3463))
+- Bump the version of Node.js installed by `nvm` to `14.21.3` ([3463](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3463))
 
 ### 🪛 Refactoring
 

package.json

@@ -466,7 +466,7 @@
     "zlib": "^1.0.5"
   },
   "engines": {
-    "node": "14.20.1",
+    "node": "^14.20.1",
     "yarn": "^1.22.10"
   }
 }

src/dev/node_versions_must_match.test.ts

@@ -29,11 +29,13 @@
  */
 
 import fs from 'fs';
+import semver from 'semver';
 import { engines } from '../../package.json';
 import { promisify } from 'util';
 const readFile = promisify(fs.readFile);
 import expect from '@osd/expect';
 
+// ToDo: `.node-version` seems to exist for no good reason; find out if we can get rid of it and this test.
 describe('All configs should use a single version of Node', () => {
   it('should compare .node-version and .nvmrc', async () => {
     const [nodeVersion, nvmrc] = await Promise.all([
@@ -48,6 +50,6 @@ describe('All configs should use a single version of Node', () => {
     const nodeVersion = await readFile('./.node-version', {
       encoding: 'utf-8',
     });
-    expect(nodeVersion.trim()).to.be(engines.node);
+    expect(semver.satisfies(nodeVersion.trim(), engines.node)).to.be(true);
   });
 });