Unpin Chrome version on CI from version 91

[arindam1993]

With chrome version 92, on 07/20/2021 all browser related tasks on CI started failing.
This is because both testem and selenium started failing to launch chrome.

Pinning chrome to version 91 temporarily fixes this issue but we need to remind ourselves to unpin this once a root cause is found.

[lisaattrillium]

@arindam1993 have you come across any issues with Chrome v93? We're having map alignment issues with chrome v 93.0.4577.82

those who have not updated Chrome are not seeing the bug.