date the changelog entry

ChangeLog.md

 # Changelog for tahoe-lafs-immutable-uploader
 
-## 0.2.0.0 (unreleased)
+## 0.2.0.0 (2023-10-02)
 
 * `decode` now checks the fingerprint in the read capability against the URI
   extension block in shares being decoded and signals an error instead of