hasExpired() should use self::getTimeNow()

[prikkprikkprikk]

While trying to test some code that caches an AccessToken and refreshes it if it has expired, I discovered that AccessToken->hasExpired() uses time() instead of self::getTimeNow(), and thus ignores self::$timeNow when testing.

This pull request fixes that.

[codecov[bot]]

Codecov Report

Merging #993 (4884dea) into master (164ccb0) will not change coverage. The diff coverage is 100.00%.

@@             Coverage Diff             @@
##              master      #993   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
  Complexity       190       190           
===========================================
  Files             20        20           
  Lines            514       514           
===========================================
  Hits             514       514           

Impacted Files	Coverage Δ
src/Token/AccessToken.php	100.00% <100.00%> (ø)