crossnobis: invalid value encountered in cast

[Katerina Marie Simkova]

Describe the bug
calc_rdm_crossnobis raises a strange error

To Reproduce

rdms = calc_rdm_crossnobis(ds, descriptor='event')

Versions

• rsatoolbox 0.1.3.dev44
• python 3.10.6
• ubuntu 22.04

stack trace
<__array_function__ internals>:200: RuntimeWarning: invalid value encountered in cast

[Katerina Marie Simkova]

It's a warning, the rdms object is created successfully