[CI] Pin inventree-plugin-creator to 1.20.1

[SchrodingersGat]

Ref: inventree/plugin-creator#116

[netlify]

✅ Deploy Preview for inventree-web-pui-preview canceled.

Name	Link
🔨 Latest commit	03ef9c1
🔍 Latest deploy log	https://app.netlify.com/projects/inventree-web-pui-preview/deploys/6ab5ea53e80f060008b66c3d

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.31%. Comparing base (94f1f1e) to head (03ef9c1).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #12932   +/-   ##
=======================================
  Coverage   87.30%   87.31%           
=======================================
  Files        1506     1506           
  Lines      103092   103092           
  Branches    11582    11582           
=======================================
+ Hits        90008    90014    +6     
+ Misses      13019    13013    -6     
  Partials       65       65           

Flag	Coverage Δ
backend	92.04% <ø> (ø)
migrations-mysql	34.30% <ø> (-0.15%)	⬇️
migrations-postgresql	34.32% <ø> (-0.14%)	⬇️
migrations-sqlite	34.32% <ø> (-0.15%)	⬇️

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Components	Coverage Δ
Backend Apps	92.69% <ø> (ø)
Backend General	94.95% <ø> (ø)
Frontend	79.60% <ø> (ø)

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