Update Renovate config

Author: sairon

.github/renovate.json

@@ -4,9 +4,9 @@
   "customManagers": [
     {
       "customType": "regex",
-      "fileMatch": ["^build\\.yaml$"],
+      "fileMatch": ["^Dockerfile$"],
       "matchStrings": [
-        "(?<image>ghcr\\.io/home-assistant/[a-z0-9]+-base:(?<alpineVersion>alpine[0-9\\.]+))-(?<currentValue>[0-9]+\\.[0-9]+\\.[0-9]+)"
+        "BUILD_FROM=(?<image>ghcr\\.io/home-assistant/base:(?<alpineVersion>alpine[0-9\\.]+))-(?<currentValue>[0-9]+\\.[0-9]+\\.[0-9]+)"
       ],
       "datasourceTemplate": "github-releases",
       "depNameTemplate": "home-assistant/docker-base"