chore(deps): update docker.io/grafana/grafana-image-renderer docker tag to v5.8.8 (#1667)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

kubernetes/apps/monitoring/grafana/app/renderer.yaml

@@ -30,7 +30,7 @@ spec:
           main:
             image:
               repository: docker.io/grafana/grafana-image-renderer
-              tag: v5.8.3@sha256:340c91e98ccd65001a3da4d0192fcf0ed13e95609a51a0d62c35a61b6ff28dff
+              tag: v5.8.8@sha256:a30a68c2de11a1aad5733452536ac50fbc2f3958e6d0aa046ef9eb56db7c6a6d
     service:
       main:
         controller: main