Update changelog

CHANGELOG.rst

 Unreleased changes
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-* DST sample added
-
 
 Version 0
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-0.2.23 / 2020-02-02
+0.2.24 / 2021-04-18
+~~~~~~~~~~~~~~~~~~~
+* DST sample added
+
+0.2.23 / 2021-02-02
 ~~~~~~~~~~~~~~~~~~~
 * Added a new mupage ARCA sample to hdf5/
 
-0.2.22 / 2020-02-02
+0.2.22 / 2021-02-02
 ~~~~~~~~~~~~~~~~~~~
 * geamon samples added
 
-0.2.21 / 2020-02-01
+0.2.21 / 2021-02-01
 ~~~~~~~~~~~~~~~~~~~
 * New MUPAGE samples added
 * gSeaGen v7 samples added