spotify: use client version from auth response

Removes the hard-coded clientVersion parameter which required manual updating and uses the version returned in the auth response instead when querying for APs.

Props to @richard-ive for pointing this out.
Ref: https://github.com/TooTallNate/node-spotify-web/pull/62#discussion-diff-8749549
Merge pull request #63 from adammw/patch-4

Use client version from auth response instead of hard-coded client version