Add rule for updating packages based on repology info.

renovate.json

@@ -6,6 +6,18 @@
     {
       "matchUpdateTypes": ["minor", "patch", "pin", "digest"],
       "automerge": true
+    },
+    {
+      "fileMatch": [
+        ".*[Dd]ocker.*"
+      ],
+      "matchStrings": [
+        "(?<depNameUppercase>[A-Z0-9_]+)_VERSION\\s*=\\s*[\"']?(?<currentValue>[a-zA-Z0-9-._]+)[\"']?"
+      ],
+      "depNameTemplate": "{{{ lowercase depNameUppercase }}}",
+      "versioningTemplate": "loose",
+      "datasourceTemplate": "repology",
+      "packageNameTemplate": "homebrew/{{{ lowercase depNameUppercase }}}"
     }
   ]
 }