bump Keda base images to 2.19.0 (#801)

Author: halamix2

external-images.yaml

@@ -1,4 +1,4 @@
 images:
-  - source: "ghcr.io/kedacore/keda:2.18.3"
-  - source: "ghcr.io/kedacore/keda-admission-webhooks:2.18.3"
-  - source: "ghcr.io/kedacore/keda-metrics-apiserver:2.18.3"
+  - source: "ghcr.io/kedacore/keda:2.19.0"
+  - source: "ghcr.io/kedacore/keda-admission-webhooks:2.19.0"
+  - source: "ghcr.io/kedacore/keda-metrics-apiserver:2.19.0"