test: move the tzdb version test into tests/ so npm test runs it

tests/timezones/tzdb.test.js

@@ -1,6 +1,6 @@
 import test from 'tape'
-import spacetime from './lib/index.js'
-import { tzdbVersion } from '../zonefile/iana.js'
+import spacetime from '../_lib/index.js'
+import { tzdbVersion } from '../../zonefile/iana.js'
 
 test('tzdb version', (t) => {
   t.ok(/^\d{4}[a-z]+$/.test(spacetime.tzdbVersion), `looks like '2026c'`)