renovate: add custom regex manager for inventory vars dependencies

Inspiration taken from/documentation:
https://docs.renovatebot.com/presets-customManagers/#custommanagersdockerfileversions
https://docs.renovatebot.com/modules/manager/regex/

renovate.json

@@ -30,6 +30,18 @@
       "versioning": "regex:^(?<major>\\d+\\.\\d+)(?:\\.(?<minor>\\d+))$"
     }
   ],
+  "customManagers": [
+    // Custom manager using regex for letting Renovate find dependencies in inventory variables.
+    {
+      "customType": "regex",
+      "managerFilePatterns": [
+        "/^inventories/.*?_vars/.*?\\.ya?ml$/"
+      ],
+      "matchStrings": [
+        "# renovate: datasource=(?<datasource>[a-zA-Z0-9-._]+?) depName=(?<depName>[^\\s]+?)(?: packageName=(?<packageName>[^\\s]+?))?(?: versioning=(?<versioning>[^\\s]+?))?\\s*.+?\\s*:\\s*[\"']?(?<currentValue>.+?)[\"']?\\s"
+      ]
+    }
+  ],
   "docker-compose": {
     "managerFilePatterns": [
       "/(^|/)(?:docker-)?compose[^/]*\\.ya?ml.j2$/"