Update README.md

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README.md

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 `keynote-parser` is a Python module for unpacking and re-packing
 [Apple Keynote](https://www.apple.com/keynote/) `.key` files. It supports Keynote
-files generated by Keynote version 12.1 (current as of September 2022).
+files generated by Keynote version 12.2.1 (current as of December 2022).
 
 Keynote uses a proprietary, compressed binary format to store its presentations.
 This format is comprised of a zip file containing images and videos, as well as