Update OpenAPI URL with correct location

[SK1Y101]

Done

Changed openapi endpoint to https://raw.githubusercontent.com/maas/maas-openapi-yaml/main/openapi.yaml

[webteam-app]

Demo starting at https://maas-io-777.demos.haus

[codecov]

Codecov Report

Merging #777 (f885924) into main (8ca49ae) will not change coverage.
The diff coverage is n/a.

❗ Current head f885924 differs from pull request most recent head aa36912. Consider uploading reports for the commit aa36912 to get more accurate results

@@           Coverage Diff           @@
##             main     #777   +/-   ##
=======================================
  Coverage   65.56%   65.56%           
=======================================
  Files           8        8           
  Lines         363      363           
=======================================
  Hits          238      238           
  Misses        125      125           

Flag	Coverage Δ
python	65.56% <ø> (ø)

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Impacted Files	Coverage Δ
webapp/app.py	69.86% <ø> (ø)

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[sparkiegeek]

Sentry issue: MAAS-IO-52