Hide warning about the missing hash in metadata.yaml for sample datasets

[sfmig]

Is your feature request related to a problem? Please describe.
When running from movement import sample_data the following warning is thrown from pooch.

Downloading data from 'https://gin.g-node.org/neuroinformatics/movement-test-data/raw/master/metadata.yaml' to file '/Users/nsirmpilatze/.movement/data/temp_metadata.yaml'.
SHA256 hash of downloaded file: 5789de438382fc06310a1fa6cc9fac085a747cd2ad44800ccb019e95ad2f3419
Use this value as the 'known_hash' argument of 'pooch.retrieve' to ensure that the file hasn't changed if it is downloaded again in the future.

This is because pooch downloads the latest metadata.yaml file from GIN and builds a data registry based on that. We don't have a hash associated to that file, because it may change often, and we want to avoid having to update the movement code repo, every time a dataset is added or updated on GIN.

So pooch has a vlid reason to complain here, but in movement's context we choose not to care about it.
That said, this warning may look scary to users, especially because it's the first output they see if they run one of our examples.

Describe the solution you'd like
Filter out this specific warning so it's not shown.