Swap to env files

__tests__/installer.test.ts

@@ -42,6 +42,7 @@ describe('setup-node', () => {
 
   beforeEach(() => {
     // @actions/core
+    process.env['GITHUB_PATH'] = ''; // Stub out ENV file functionality so we can verify it writes to standard out
     inputs = {};
     inSpy = jest.spyOn(core, 'getInput');
     inSpy.mockImplementation(name => inputs[name]);
@@ -487,3 +488,4 @@ describe('setup-node', () => {
     });
   });
 });
+