Update certifi, requests and urllib3 dependencies

[JJK96]

Resolves the following messages by PIP:

gophish 0.5.1 requires certifi==2020.6.20, but you have certifi 2021.5.30 which is incompatible.
gophish 0.5.1 requires requests==2.24.0, but you have requests 2.26.0 which is incompatible.
gophish 0.5.1 requires urllib3==1.25.10, but you have urllib3 1.26.7 which is incompatible.

Fix #30