updated changelog

Author: alixdamman

doc/source/changes/version_0_30.rst.inc

@@ -232,4 +232,6 @@ Fixes
 
 * fixed arithmetic operations between two sessions returning a nan value for each axis and group (closes :issue:`725`).
 
-* fixed dumping sessions with metadata using HDF format (closes :issue:`702`).
+* fixed dumping sessions with metadata in HDF format (closes :issue:`702`).
+
+* fixed minimum version of pandas to install. The minimum version is now 0.20.0.