[FIX] Testing: use newest release of sinon to fix sinon issue #1534

The sinon release 4.1.3 - which is currently packaged with UI5 as
sinon-4 - has an issue when a fake server is created from a sandbox. The
created server unintentionally fakes timers as well and therefore
doesn't auto-respond.

See sinonjs/sinon#1534 for details.

Sinon release 4.1.6 fixes the issue, this change applies the newest
available release 4.4.6. 

Change-Id: If9207574f1e0b7d253ecb15041b15363086fa541

LICENSE.txt

@@ -483,7 +483,7 @@ License: BSD 3-clause "New" or "Revised" License
 <ORGANIZATION> = Christian Johansen
 <YEAR> = 2010-2014
 
-Component: Sinon.JS 4.1.3
+Component: Sinon.JS 4.4.6
 Licensor: Christian Johansen
 Website: http://github.com/cjohansen/Sinon.JS/
 License: BSD 3-clause "New" or "Revised" License