(from AES) Merge pull request #2104 from datawire/esmet/dev/master/pin-pip
(from AES) Merge pull request #2104 from datawire/esmet/dev/master/pin-pip

ambassador/builder: pin pip to 20.2.4
datawire/ambassador,datawire/ambassador,datawire/ambassador,datawire/ambassador,datawire/ambassador