Merge pull request #3842 from DataDog/remeh/urllib3-1-24-3

Upgrade urllib3 to 1.24.3

Author: remeh

requirements.txt

@@ -32,7 +32,7 @@ pyyaml==3.11
 # note: requests is also used in many checks
 # upgrade with caution
 requests==2.20.1
-urllib3==1.24.2
+urllib3==1.24.3
 # note: simplejson is used in many checks to inteface APIs
 simplejson==3.6.5
 supervisor==3.3.3