Release langchain-text-splitters==0.2.1

Changes since langchain-text-splitters==0.2.0

text-splitters[patch]: Release 0.2.1 (#22490)
text-splitters[patch]: fix HTMLSectionSplitter parsing of xslt paths (#22176)
fix error message (#22437)
text-splitters[patch]: Extend TextSplitter:keep_separator functionality (#21130)
infra: fix CI on text-splitters (#21935)