Update Helm release mongodb to v13.15.4 (#776)

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

Author: renovate[bot]

src/terraform/versions-databases.yaml

@@ -10,7 +10,7 @@ helm_versions:
       name: bitnami
       url: https://charts.bitnami.com/bitnami
     chart_name: mongodb
-    chart_version: 13.15.3
+    chart_version: 13.15.4
   mssql:
     repository:
       name: simcube

src/terraform/versions.yaml

@@ -142,7 +142,7 @@ helm_versions:
       name: bitnami
       url: https://charts.bitnami.com/bitnami
     chart_name: mongodb
-    chart_version: 13.15.3
+    chart_version: 13.15.4
   mssql:
     repository:
       name: simcube