Packaging changes for 2.4.0 and changelog update

debian/changelog

+ligo-gracedb (2.4.0-1) unstable; urgency=low
+
+  * Add client method and CLI method for updating a GRB event
+
+ -- Tanner Prestegard <tanner.prestegard@ligo.org>  Wed, 21 Aug 2019 13:37:46 -0500
+
 ligo-gracedb (2.3.0-1) unstable; urgency=low
 
   * Add feature for reloading an expired X.509 certificate

docs/source/changelog.rst

 Changelog
 =========
 
+2.4.0 (August 21, 2019)
+---------------------
+
+- Change minimum required version of ``six`` to 1.9.0
+- Add client method for updating GRB event parameters
+- Add CLI method for updating GRB event parameters
+
+
 2.3.0 (July 17, 2019)
 ---------------------
 

ligo-gracedb.spec

 %define name              ligo-gracedb
-%define version           2.3.0
-%define unmangled_version 2.3.0
+%define version           2.4.0
+%define unmangled_version 2.4.0
 %define release           1
 
 Summary:   Gravity Wave Candidate Event Database

ligo/gracedb/version.py

-__version__ = '2.3.0'
+__version__ = '2.4.0'