* remove is_derived meta data from SignalRef

* version bump

 Description:
A publicly-visible method or associated fn is no longer available under its prior name. It may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.48.0/src/lints/inherent_method_missing.ron

Failed in:
  SignalRef::derived_from_index, previously in file /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wellen-0.23.0/src/hierarchy.rs:308
  SignalRef::is_derived_signal, previously in file /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wellen-0.23.0/src/hierarchy.rs:325
  SignalRef::to_derived, previously in file /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wellen-0.23.0/src/hierarchy.rs:335

     Summary semver requires new major version: 1 major and 0 minor checks failed