chore: Remove unecessary transitive dependency: conllu<5.0.0

conllu was probably added to avoid issues created by flair not
limiting conllu's version to 5.0.0. However, the latest versions
of flair already added this version restriction, so we can
safely remove it now. I'm instead adding a minimum version
requirement on flair 0.14.0 which has added this restriction.

requirements.txt

@@ -5,12 +5,11 @@ torch
 transformers
 tqdm
 scikit-learn
-flair
+flair>=0.14.0
 requests
 scipy<1.13
 matplotlib<3.9
 panel!=1.4.3
 Levenshtein
 autofj
-conllu<5.0.0
 nltk>=3.9.1