prepare release

Author: dbu

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 # Version 1.x
 
-# 1.2.0 (unreleased)
+# 1.2.0
 
 * DateTimeOptions now features a list of deserialization formats instead of a single string one. Passing a string instead of an array to its `__construct`or is deprecated, and will be forbidden in the next version
   Similarly, `getDeserializeFormat(): ?string` is deprecated in favor of `getDeserializeFormats(): ?array`