Ignore engine spec when testing with latest Node

We are defining the version of Node we support with the `engines`
directive[1] in `package.json` - as we should be. However, when testing
against the latest version of Node, we need to override that. Turn off
`engine-strict`[2] via the command line, so that Node will install our
dependencies.

[1] https://docs.npmjs.com/cli/v10/configuring-npm/package-json?v=true#engines
[2] https://docs.npmjs.com/cli/v10/using-npm/config#engine-strict

.github/workflows/test-current-node.yml

@@ -31,7 +31,7 @@ jobs:
           check-latest: true
 
       - name: Install dependencies
-        run: npm ci
+        run: npm ci --no-engine-strict
 
       - name: Run build
         run: npm run build