Unpin Zuul

This will upgrade us to the latest commit (5.0.0 +).

Change-Id: Ied564a42a6e76346bfbf36fcc66f35389e2fb96c
diff --git a/k8s/zuul.yaml b/k8s/zuul.yaml
index 1536c14..38e1af3 100644
--- a/k8s/zuul.yaml
+++ b/k8s/zuul.yaml
@@ -125,7 +125,7 @@
     spec:
       containers:
       - name: merger
-        image: zuul/zuul-merger:4.10.4
+        image: zuul/zuul-merger:latest
         volumeMounts:
         - name: zuul-config
           mountPath: /etc/zuul
@@ -168,7 +168,7 @@
     spec:
       containers:
       - name: web
-        image: zuul/zuul-web:4.10.4
+        image: zuul/zuul-web:latest
         ports:
         - name: zuul-web
           containerPort: 9000
@@ -218,7 +218,7 @@
         runAsGroup: 10001
       containers:
       - name: executor
-        image: zuul/zuul-executor:4.10.4
+        image: zuul/zuul-executor:latest
         ports:
         - name: logs
           containerPort: 7900
@@ -282,7 +282,7 @@
     spec:
       containers:
       - name: scheduler
-        image: zuul/zuul-scheduler:4.10.4
+        image: zuul/zuul-scheduler:latest
         ports:
         - name: gearman
           containerPort: 4730