Extras: Fix list_api_changes script for 19.08

Change-Id: I9907a60347933bb2be8c967bf5e0d507b57b982b
Signed-off-by: Dave Wallace <dwallacelf@gmail.com>
diff --git a/extras/scripts/list_api_changes.py b/extras/scripts/list_api_changes.py
index 0c5db3c..11150dc 100755
--- a/extras/scripts/list_api_changes.py
+++ b/extras/scripts/list_api_changes.py
@@ -1,8 +1,8 @@
 #!/usr/bin/env python
 import os, fnmatch, subprocess
 
-starttag = 'v19.01-rc0'
-endtag = 'v19.01'
+starttag = 'v19.08-rc0'
+endtag = 'HEAD'
 emit_md = True
 apifiles = []