fix: remove module extension from imported file in fixture

Author: syi0808

test/fixtures/module-mocking/basic-esm-without-extension.js

@@ -0,0 +1 @@
+export let string = 'original esm string';

test/fixtures/module-mocking/wrong-import-after-module-mocking.js

@@ -4,5 +4,5 @@ try {
   if (mock.module) mock.module('Whatever, this is not significant', { namedExports: {} });
 } catch {}
 
-const { string } = await import('./basic-esm');
+const { string } = await import('./basic-esm-without-extension');
 console.log(`Found string: ${string}`); // prints 'original esm string'