Auto remove obsoleted GO terms

We should automatically check for obsoloete GO terms and remove them.

I did this manually for the last release, with some `sed` commands around here:
https://github.com/RNAcentral/rnacentral-import-pipeline/blob/dev/workflows/lookup-ontology-info.nf#L13

Example command: `sed -i '/GO:0000512/d' unique-terms.txt`

