Prepare tools/r8_release.py for branch 8.6

Change-Id: Ie55d7af341a30478e1a09c1ec3efe0fb155e213d
diff --git a/tools/r8_release.py b/tools/r8_release.py
index 263aa76..6cebc5e 100755
--- a/tools/r8_release.py
+++ b/tools/r8_release.py
@@ -17,7 +17,7 @@
 
 import utils
 
-R8_DEV_BRANCH = '8.5'
+R8_DEV_BRANCH = '8.6'
 R8_VERSION_FILE = os.path.join('src', 'main', 'java', 'com', 'android', 'tools',
                                'r8', 'Version.java')
 THIS_FILE_RELATIVE = os.path.join('tools', 'r8_release.py')