Added UQFN-20_3x3mm_P0.4mm (script generated)

[cnieves1]

Datasheet: https://resurgentsemi.com/wp-content/uploads/2018/09/MPR121_rev5-Resurgent.pdf
Source: easyw/kicad-3d-models-in-freecad#352

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Thanks for creating a pull request to contribute to the KiCad libraries! To speed up integration of your PR, please check the following items as you complete them:

• A screenshot of the model(s) aligned with KiCad footprints is very useful
• Was the 3D model(s) created in a mechanical modelling program?
• Source files (or scripts) have been contributed
• Step model submitted in 1:1 scale
• WRL model submitted in 1:2.54 scale
• 3D model alignment checked against KiCad footprint
• WRL model uses correct material properties
• Geometry check performed against mechanical models

[chschlue]

KiCad/kicad-footprints#2185