chore(deps): Update peer dependency apollo-client to ^2.6.0

[brentertz]

Greetings. I am getting a peer dependency warning about apollo-client even though I have the latest version, v2.6.0, installed.

npm WARN [email protected] requires a peer of apollo-client@beta but none is installed. You must install peer dependencies yourself.

The apollo-client dist-tags are:

• beta: 2.6.0-rc.3
• latest: 2.6.0

I don't believe that we need to use the beta anymore now that it has been released. This PR simply updates the peer dependency version to ^2.6.0.

[apollo-cla]

@brentertz: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Meteor Contributor Agreement here: https://contribute.meteor.com/

[hwillson]

Thanks very much @brentertz!

[sarink]

my package.json

    "react-apollo": "^2.5.6",

the error

frontend_1  | npm WARN [email protected] requires a peer of apollo-client@beta but none is installed. You must install peer dependencies yourself.

and yet?
https://github.com/apollographql/react-apollo/blob/master/package.json

"version": "2.5.6",
"peerDependencies": {
  "apollo-client": "^2.6.0",
  ...

how is this still happening? 🤔

[brentertz]

My guess would be that a new version of react-apollo has yet to be published.