textproc/py-textual-textarea: Update to 0.18.1

ChangeLog:

• https://github.com/tconbeer/textual-textarea/releases#release-v0.17.3
• https://github.com/tconbeer/textual-textarea/releases#release-v0.18.0
• https://github.com/tconbeer/textual-textarea/releases#release-v0.18.1

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