[prometheus-mongodb-exporter] Update dependency percona/mongodb_exporter to v0.50.0 (#6817)

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

Author: renovate[bot]

charts/prometheus-mongodb-exporter/Chart.yaml

@@ -1,6 +1,6 @@
 apiVersion: v2
 # renovate: github=percona/mongodb_exporter
-appVersion: 0.49.0
+appVersion: 0.50.0
 description: A Prometheus exporter for MongoDB metrics
 home: https://github.com/percona/mongodb_exporter
 keywords:
@@ -18,4 +18,4 @@ maintainers:
 name: prometheus-mongodb-exporter
 sources:
   - https://github.com/percona/mongodb_exporter
-version: 3.18.0
+version: 3.19.0