Update fastapi, black and gunicorn

[gmmajal]

Related to: #19

Things changed:

• The versions of fastapi and black in pyproject.toml have been bumped.
• The poetry.lock file has been updated.
• gunicorn has been bumped inside the Dockerfile due this security vulnerability: https://data.safetycli.com/v/71600/f17/.
• We will ignore the jinja2 vulnerability being flagged by safety as it is disputed. Relevant issues on github on this are Safety reports its own dependecy (jinja2) as vulnerable without fix available pyupio/safety#527 and Vulnerability found in jinja2 version 3.1.4 pallets/jinja#1994.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.54%. Comparing base (4b9bf05) to head (31fcdbd).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #21   +/-   ##
=======================================
  Coverage   94.54%   94.54%           
=======================================
  Files          23       23           
  Lines         898      898           
=======================================
  Hits          849      849           
  Misses         49       49           

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