Update CHANGES.md for the version 1.3.0

Author: mrkn

CHANGES.md

@@ -1,9 +1,25 @@
 # The change history of PyCall
 
-## master
+## 1.3.0
 
 * Add `PyCall.without_gvl` for explicitly releasing the RubyVM GVL
 
+* Fix for missing if in PyObjectWrapper
+
+  *Kouhei Sutou*
+
+* Fix for Anaconda environment
+
+  *Ryo MATSUMIYA*
+
+* Fix against `unknown symbol "PyInt_AsSsize_t"` (Fiddle::DLError)
+
+  *Kouhei Sutou*
+
+* Fix for `TypeError: Compared with non class/module`
+
+  *Archonic*
+
 ## 1.2.1
 
 * Prevent circular require in pycall/iruby.rb