Is your feature request related to a problem? Please describe.
In order to modernize the application bundle structure on macOS, the environment setup in crates/rnote-ui/src/env.rs needs to be modified.

Describe the solution you'd like
On macOS

• lib_dir needs to return ../Frameworks instead of ../Resources/lib
• GDK_PIXBUF_MODULE_FILE needs to point to ../Resources/etc/loaders.cache

Describe alternatives you've considered
None.

Additional context
I've attached a patch that I've used to check that this works for demonstrational purposes. It needs to be reengineered for GDK_PIXBUF_MODULE_FILE as that shouldn't be set relative to lib_dir. But I don't know Rust and even simple changes give me "you can't do this because it's borrowed..." errors, that's why I cannot submit a PR.

rnote_bundle.patch