Revert "Removed unused pytest-monkeytype"

This reverts commit a08fe11.

Author: aaront

Pipfile

@@ -15,6 +15,7 @@ black = "*"
 requests-mock = "*"
 pytest-datadir = "*"
 pytest-benchmark = "*"
+pytest-monkeytype = "*"
 pandas = "*"
 types-requests = "*"
 types-pytz = "*"