chore(deps): update ghcr.io/fluxcd/notification-controller docker tag to v1.7.3

Author: renovate[bot]

kubernetes/main/flux-system/config/gotk-components.yaml

@@ -10139,7 +10139,7 @@ spec:
             resourceFieldRef:
               containerName: manager
               resource: limits.memory
-        image: ghcr.io/fluxcd/notification-controller:v1.7.1
+        image: ghcr.io/fluxcd/notification-controller:v1.7.3
         imagePullPolicy: IfNotPresent
         livenessProbe:
           httpGet: