chore(package): update sinon to version 7.5.0

Closes #24

Author: greenkeeper[bot]

package.json

@@ -23,7 +23,7 @@
     "redis": "~2.8.0",
     "mocha": "~5.2.0",
     "chai": "~4.2.0",
-    "sinon": "~7.1.1",
+    "sinon": "~7.5.0",
     "sinon-chai": "~3.3.0",
     "chai-as-promised": "~7.1.1",
     "jshint": "~2.9.5"