chore: use path.resolve for tests localDir

lib/manager/nuget/extract.spec.ts

 import { readFileSync } from 'fs';
+import path from 'path';
 import * as upath from 'upath';
 import { ExtractConfig } from '../common';
 import { extractPackageFile } from './extract';
@@ -8,7 +9,7 @@ describe('lib/manager/nuget/extract', () => {
     let config: ExtractConfig;
     beforeEach(() => {
       config = {
-        localDir: upath.resolve('lib/manager/nuget/__fixtures__'),
+        localDir: path.resolve('lib/manager/nuget/__fixtures__'),
       };
     });
     it('returns empty for invalid csproj', async () => {