Update CHANGELOG.md

Author: CodyCBakerPhD

CHANGELOG.md

@@ -1,5 +1,7 @@
 # Upcoming
 
+# v0.4.21
+
 ### New Checks
 * Add check for unique ids for DynamicTables. [PR #316](https://github.com/NeurodataWithoutBorders/nwbinspector/pull/316)
 
@@ -9,6 +11,7 @@
 * Write a custom `get_data_shape` method that does not return `maxshape`, which fixes errors in parsing shape. [PR #315](https://github.com/NeurodataWithoutBorders/nwbinspector/pull/315)
 
 
+
 # v0.4.20
 
 ### Improvements