This patch adds REQUESTS_CA_BUNDLE as it's described
in requests documentation [1].

This is needed because some ansible modules inside uses
python request library and some users of course using
their own CAs.

[1] https://requests.readthedocs.io/en/latest/user/advanced/#ssl-cert-verification

Closes-Bug: #1967132

Change-Id: I901c2bc8ac477f15d2833e68566b19e437f4b6d1