chore(package): update sinon to version 8.0.0 (#221)

Author: greenkeeper[bot]

package.json

@@ -44,7 +44,7 @@
     "hoodiecrow-imap": "^2.1.0",
     "mocha": "^7.0.1",
     "pre-commit": "^1.2.2",
-    "sinon": "^7.3.2",
+    "sinon": "^8.0.0",
     "standard": "^13.0.1",
     "webpack": "^4.33.0",
     "webpack-cli": "^3.3.3"