fix: avoid warning message in corr metadata

[tensulin]

when metadata is correlated the case might happen that subgroups have 1 or less members, this results in a warning

The attached CSV files are in reality TSV files, but github doesn't allow tsv file ending

example_metadata.csv
correlation_metadata.TXT
correlated_metadata_result_table.csv

Example code:

res_corrmeta = correlate_metadata(
    prj_metadata_filtered[list(set(prj_metadata_filtered.columns) - set(cols_ignore))],
    categorials=list(cols_categorial),
    ordinals=cols_ordinal,
    dates=cols_date,
    intervals=list(cols_interval)
)
display(res_corrmeta[1])

Expected warning without the fix:
Screenshot from 2024-08-28 12-26-52