Update changelog entry

Author: EmilianoSanchez

CHANGES.txt

@@ -1,3 +1,6 @@
+0.2.1 (February 24, 2025):
+ - Fixed the SDK language version to correctly reflect the package version.
+
 0.2.0 (February 14, 2025):
  - Added new variations of the get treatment functions to support evaluating flags in given flag set/s: `Split.get_treatments_by_flag_set/3`, `Split.get_treatments_by_flag_sets/3`, `Split.get_treatments_with_config_by_flag_set/3`, and `Split.get_treatments_with_config_by_flag_sets/3`.
  - Updated the `:socket_path` option for `Split.Supervisor.start_link/1` to be optional, defaulting to `"/var/run/splitd.sock"`.