chore(package): update sinon to version 7.4.2

Closes #486

Author: greenkeeper[bot]

package.json

@@ -47,7 +47,7 @@
     "mocha": "^5.0.0",
     "semantic-release": "^15.5.1",
     "simple-git": "^1.45.0",
-    "sinon": "6.0.1",
+    "sinon": "7.4.2",
     "sinon-chai": "^3.2.0",
     "validate-commit-msg": "^2.6.1"
   },