Pin nodepool-launcher to 10.0.0

Newer versions of nodepool-launcher use a buggy openstacksdk that is
looking for a config file even when we're not using openstack as the
provider.

We can move back to latest once a fixed image is released.

Change-Id: I7726a863eb3bf5633f3215286c4b59953090306f

k8s/nodepool.yaml

diff --git a/k8s/nodepool.yaml b/k8s/nodepool.yaml
index 956cbac..f83dc9a 100644
--- a/k8s/nodepool.yaml
+++ b/k8s/nodepool.yaml
@@ -27,7 +27,7 @@
     spec:
       containers:
       - name: launcher
-        image: quay.io/zuul-ci/nodepool-launcher:latest
+        image: quay.io/zuul-ci/nodepool-launcher:10.0.0
         env:
         - name: OS_CLIENT_CONFIG_FILE
           value: /etc/nodepool/clouds.yaml