fix(devcontainer): install poetry via devcontainer feature

[kenibrewer]

This change will speed up devcontainer loading and resolve some inconsistencies in how vscode treats python environments in the devcontainer

Closes #334

modified from EmbeddedArtistry

Description

VSCode has apparently introduced changes in the way that python environments are loaded

What is the nature of your change?

• Bug fix (fixes an issue).

Checklist

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• I have read the CONTRIBUTING.md guidelines.
• My code follows the style guidelines of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• My changes generate no new warnings.
• I have deleted all non-relevant text in this pull request template.

[codecov-commenter]

Codecov Report

Merging #337 (d5e552b) into main (afe5df3) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #337   +/-   ##
=======================================
  Coverage   95.40%   95.40%           
=======================================
  Files          56       56           
  Lines        3134     3134           
=======================================
  Hits         2990     2990           
  Misses        144      144           

Flag	Coverage Δ
unittests	95.40% <ø> (ø)

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[d33bs]

Nice job! LGTM, with one minor comment up to your opinion.