qc_taxa_phylo - phylo columns with no data crash

[leppott]

Describe the bug
If include phylo columns that are valid but have not data the function crashes when building df_unique_parent (line 182).

To Reproduce
Steps to reproduce the behavior:

1. Use a data source with a phylo column that has no data (i.e., all NA).

Expected behavior
Need to remove those columns that are all NA.

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Additional context
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