FXAAEffect is not exported in types

[canadaduane]

Description of the bug

Although defined and re-exported here, the FXAAEffect class is not exported in the typescript types.

See https://github.com/pmndrs/postprocessing/blob/main/types/postprocessing.d.ts

Library versions used

• Three: 0.141.0
• Post Processing: 6.28.1

[vanruesc]

Updated types in postprocessing@6.28.2. Let me know if something's still broken.