refactor: info not warn if npm 401 response

lib/manager/npm/registry.js

@@ -84,6 +84,10 @@ async function getDependency(name) {
     logger.trace({ dep }, 'dep');
     return dep;
   } catch (err) {
+    if (err.statusCode === 401) {
+      logger.info({ err, name }, `Dependency lookup unauthorized`);
+      return null;
+    }
     if (err.statusCode === 404) {
       logger.info({ err, name }, `Dependency not found`);
       return null;

test/manager/npm/registry.spec.js

@@ -45,6 +45,13 @@ describe('api/npm', () => {
     const res = await npm.getDependency('foobarhome');
     expect(res).toMatchSnapshot();
   });
+  it('should return null if lookup fails 401', async () => {
+    nock('https://registry.npmjs.org')
+      .get('/foobar')
+      .reply(401);
+    const res = await npm.getDependency('foobar');
+    expect(res).toBeNull();
+  });
   it('should return null if lookup fails', async () => {
     nock('https://registry.npmjs.org')
       .get('/foobar')