Make sure default automerge params reflect their type

[chrishalcrow]

In spikeinterface-gui, the parameter type of each autmerge algorithm is computed by computing the type of the default.

Before this PR there were some mismatches between the type (e.g. min_snr is a float param) and the type of the default value (min_snr has default value 2). This means the user cannot change min_snr to float values in the GUI. This PR ensures all default param values have the type intended by their param.

[zm711]

Would it be worth adding type hints somewhere around here. Otherwise I think it would be too easy for these things to get out of sync in the future, no?

[chrishalcrow]

Would it be worth adding type hints somewhere around here. Otherwise I think it would be too easy for these things to get out of sync in the future, no?

Yeah it's a good point. It's a bit awkward: some of these are type-hinted in their function signatures but the values are given here. This is fine internally: it's only a problem when used externally by e.g. si-gui. It's not easy to test because the function signatures are scattered all over the place, and only covers some parameters e.g. min_spikes is just used here, and it passed through some generic params dict:

spikeinterface/src/spikeinterface/curation/auto_merge.py

Line 249 in 6b47603

to_remove = num_spikes < params["min_spikes"]

so isn't typed anywhere...

EDIT: one option is to wait until 3.11 (~ a year's time) and then implement TypedDicts everywhere we use parameters...