[prometheus-nginx-exporter] Update dependency nginx/nginx-prometheus-exporter to v1.5.1 (#6240)

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

Author: renovate[bot]

charts/prometheus-nginx-exporter/Chart.yaml

@@ -2,9 +2,9 @@
 apiVersion: v2
 description: A Helm chart for NGINX Prometheus Exporter
 name: prometheus-nginx-exporter
-version: 1.12.0
+version: 1.13.0
 # renovate: github-releases=nginx/nginx-prometheus-exporter
-appVersion: 1.4.2
+appVersion: 1.5.1
 home: https://github.com/nginxinc/nginx-prometheus-exporter
 sources:
   - https://github.com/nginxinc/nginx-prometheus-exporter