ci: update default flux-security version to 0.9.0

Problem: flux-security v0.9.0 has been tagged, but the by default
docker-run-checks.sh is still using 0.8.0.

Update the default version of flux-security to v0.9.0.

Author: grondo

src/test/docker/docker-run-checks.sh

@@ -16,7 +16,7 @@ JOBS=2
 MOUNT_HOME_ARGS="--volume=$HOME:/home/$USER -e HOME"
 
 if test "$PROJECT" = "flux-core"; then
-  FLUX_SECURITY_VERSION=0.8.0
+  FLUX_SECURITY_VERSION=0.9.0
   POISON=t
 fi