Invalid tags in plugin.json

[cschol]

[MockbaModular] Issues found in `plugin.json`:

Feidah: invalid module tags: Attenuator, Polyphonic
Mixah: invalid module tags: Mixer, Polyphonic
Selectah: invalid module tags: Utility, Polyphonic
CZSaw: invalid module tags: Oscillator, Polyphonic
CZSquare: invalid module tags: Oscillator, Polyphonic
CZPulse: invalid module tags: Oscillator, Polyphonic
CZReso: invalid module tags: Oscillator, Polyphonic
-- Valid tags are defined in https://raw.githubusercontent.com/VCVRack/Rack/v1/src/tag.cpp

[MockbaTheBorg]

Corrected the tags syntax