Update openeo.extra.spectral_indices to Awesome Spectral Indices v0.4.0

Author: soxofaan

CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Simplified `BatchJob` methods `start()`, `stop()`, `describe()`, ...
   Legacy aliases `start_job()`, `describe_job()`, ... are still available and don't trigger a deprecation warning for now.
   ([#280](https://github.com/Open-EO/openeo-python-client/issues/280))
+- Update `openeo.extra.spectral_indices` to [Awesome Spectral Indices v0.4.0](https://github.com/awesome-spectral-indices/awesome-spectral-indices/releases/tag/0.4.0)
 
 ### Removed