test: revert using nock and fixtures

Author: aminya

__tests__/__fixtures__/mock-node-v12.18.3-linux-x64.tar.gz

@@ -9,7 +9,6 @@ import * as main from '../src/main';
 import * as im from '../src/installer';
 import * as auth from '../src/authutil';
 import {context} from '@actions/github';
-import nock = require('nock');
 
 let nodeTestManifest = require('./data/versions-manifest.json');
 let nodeTestDist = require('./data/node-dist-index.json');

__tests__/__fixtures__/mock-node-v12.18.3-linux-x86.tar.gz

@@ -38,7 +38,6 @@
     "@zeit/ncc": "^0.21.0",
     "jest": "^24.9.0",
     "jest-circus": "^24.7.1",
-    "nock": "^13.0.4",
     "prettier": "^1.19.1",
     "ts-jest": "^24.3.0",
     "typescript": "^3.8.3"