Added Python 3.4 EOL notice to CHANGELOG

Author: tleonhardt

CHANGELOG.md

@@ -5,6 +5,9 @@
     * `StdSim.buffer.write()` now flushes when the wrapped stream uses line buffering and the bytes being written
       contain a newline or carriage return. This helps when `pyscript` is echoing the output of a shell command
       since the output will print at the same frequency as when the command is run in a terminal.
+* **Python 3.4 EOL notice**
+    * Python 3.4 reached its [end of life](https://www.python.org/dev/peps/pep-0429/) on March 18, 2019
+    * This is the last release of `cmd2` which will support Python 3.4
 
 ## 0.9.12 (April 22, 2019)
 * Bug Fixes