[Fix] use file:// URLs for dynamic import()

This is required on Windows if the argument passed to `import()` is
an absolute path. Without it `tape test.js` fails if test.js is ESM.

Covered by existing tests: `node test/import.js` fails without this.

See nodejs/node@a084632

bin/import-or-require.js

@@ -1,14 +1,15 @@
 'use strict';
 
 const { extname: extnamePath } = require('path');
+const { pathToFileURL } = require('url');
 const getPackageType = require('get-package-type');
 
 // eslint-disable-next-line consistent-return
 module.exports = function importOrRequire(file) {
     const ext = extnamePath(file);
 
     if (ext === '.mjs' || (ext === '.js' && getPackageType.sync(file) === 'module')) {
-        return import(file);
+        return import(pathToFileURL(file).href);
     }
     require(file);
 };