docs: update website requirements.txt

[keetonian]

Issue #, if available:
N/A
Description of changes:
Update Jinja version
Description of how you validated changes:

Checklist:

• Write/update tests
• make pr passes
• Update documentation

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-io]

Codecov Report

Merging #928 into develop will decrease coverage by 0.03%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #928      +/-   ##
===========================================
- Coverage    94.66%   94.62%   -0.04%     
===========================================
  Files           69       69              
  Lines         3018     2997      -21     
  Branches       562      554       -8     
===========================================
- Hits          2857     2836      -21     
  Misses          85       85              
  Partials        76       76

Impacted Files	Coverage Δ
...el/preferences/deployment_preference_collection.py	88.88% <0%> (-2.03%)	⬇️
samtranslator/swagger/swagger.py	97.57% <0%> (-0.03%)	⬇️
samtranslator/sdk/resource.py	100% <0%> (ø)	⬆️

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