Master is not compiling

[Catscratch]

Hi.

The dependency of the master was migrated to @nutrient-sdk/viewer but the imports are still from pspdfkit. Thus the master does not compile.

Also the skipLibCheck is still set to true. Try to set it to false and the master will still not compile because of missing React imports in the lib.

[ruempel]

Fixing the import fixes building the app: #35