build(renovate): custom version extractor (#23)

Co-authored-by: winston <hey@winston.sh>

renovate.json

@@ -1,6 +1,9 @@
 {
   "$schema": "https://docs.renovatebot.com/renovate-schema.json",
-  "extends": [
-    "config:recommended"
-  ]
+  "extends": ["config:recommended"],
+  "homebrew": {
+    "commitMessageTopic": "Homebrew Formula {{depName}}",
+    "extractVersion": "^\\w-(?<version>.+)",
+    "fileMatch": ["^Formula/[^/]+[.]rb$"]
+  }
 }