"final" directory outdated

Compare .env.example with the current APOLLO_ environment variables, then run the tests referenced in src/__tests__/resolvers.mutation.js and src/__tests__/integration.js. Done means the environment example reflects the current variables and the login tests return the expected token without the reported failures.

.env.example doesn't seem to match the latest APOLLO_ environment variables, and I'm getting some failing tests:

`(node:214719) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.
 FAIL  src/__tests__/resolvers.mutation.js
  ● [Mutation.login] › returns base64 encoded email as user token if successful

    expect(received).toEqual(expected) // deep equality

    Expected: "YUBhLmE="
    Received: undefined

      103 |     // check the resolver response
      104 |     const res = await resolvers.Mutation.login(null, args, mockContext);
    > 105 |     expect(res.token).toEqual('YUBhLmE=');
          |                       ^
      106 | 
      107 |     // check if the dataSource was called with correct args
      108 |     expect(findOrCreateUser).toBeCalledWith(args);

      at Object.toEqual (src/__tests__/resolvers.mutation.js:105:23)

(node:214721) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.
 FAIL  src/__tests__/integration.js
  ● Console

    console.warn node_modules/apollo-server/node_modules/apollo-engine-reporting/dist/agent.js:57
      [deprecated] The `schemaTag` property within `engine` configuration has been renamed to `graphVariant`.

  ● Mutations › returns login token

    TypeError: Cannot read property 'login' of undefined

      125 |       variables: {email: 'a@a.a'},
      126 |     });
    > 127 |     expect(res.data.login.token).toEqual('YUBhLmE=');
          |                     ^
      128 |   });
      129 | 
      130 |   it('books trips', async () => {

      at Object.login (src/__tests__/integration.js:127:21)