Update cirros version

This is the next release in the 0.3.x stable series, containing a fix
for getting out of disk errors when cirros reads metadata from a
config-drive[0].

[0] https://bugs.launchpad.net/cirros/+bug/1808119

Change-Id: Id2f20ebafdd78c2dadf81b8f80f22e7bd6db7755
diff --git a/stackrc b/stackrc
index ffe4050..d520f2f 100644
--- a/stackrc
+++ b/stackrc
@@ -668,7 +668,7 @@
 #IMAGE_URLS="http://smoser.brickies.net/ubuntu/ttylinux-uec/ttylinux-uec-amd64-11.2_2.6.35-15_1.tar.gz" # old ttylinux-uec image
 #IMAGE_URLS="http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-disk.img" # cirros full disk image
 
-CIRROS_VERSION=${CIRROS_VERSION:-"0.3.5"}
+CIRROS_VERSION=${CIRROS_VERSION:-"0.3.6"}
 CIRROS_ARCH=${CIRROS_ARCH:-"x86_64"}
 
 # Set default image based on ``VIRT_DRIVER`` and ``LIBVIRT_TYPE``, either of