Rename keep_only_tokens to keep_only_ner_tokens

Closes #72 (closed)

changed milestone to %DAN-P2: Clean code and remove unused code

added P2 label

requested review from @starride

assigned to @melodie.boillet

requested review from @schneider-y and removed review request for @starride

added 5 commits

• 9dfc3d59...df6bda94 - 4 commits from branch main
• bbbeea3a - Rename keep_only_tokens to keep_only_ner_tokens

Compare with previous version

enabled an automatic merge when the pipeline for bbbeea3a succeeds

merged