Migrate renovate config (#423)

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

Author: renovate[bot]

.github/renovate.json

@@ -5,8 +5,9 @@
   "labels": ["dependencies", "no-stale"],
   "commitMessagePrefix": "⬆️",
   "commitMessageTopic": "{{depName}}",
-  "regexManagers": [
+  "customManagers": [
     {
+      "customType": "regex",
       "fileMatch": ["/Dockerfile$", "/build.yaml$"],
       "matchStringsStrategy": "any",
       "matchStrings": [
@@ -16,6 +17,7 @@
       "datasourceTemplate": "docker"
     },
     {
+      "customType": "regex",
       "fileMatch": ["/Dockerfile$"],
       "matchStringsStrategy": "any",
       "matchStrings": [
@@ -26,6 +28,7 @@
       "depNameTemplate": "alpine_3_20/{{package}}"
     },
     {
+      "customType": "regex",
       "fileMatch": ["/Dockerfile$"],
       "matchStrings": [
         "ARG TAILSCALE_VERSION=[\"']?(?<currentValue>.+?)[\"']?\\s+"