renovate: teach it to update the lint version

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

Author: Luap99

.github/renovate.json5

@@ -12,7 +12,7 @@
 
         podman run -it \
             -v ./.github/renovate.json5:/usr/src/app/renovate.json5:z \
-            docker.io/renovate/renovate:latest \
+            ghcr.io/renovatebot/renovate:latest \
             renovate-config-validator
      3. Commit.
 
@@ -53,6 +53,19 @@
   // Don't leave dep. update. PRs "hanging", assign them to people.
   "assignees": ["rhatdan", "vrothberg", "Luap99"],
 
+  "customManagers": [
+    {
+      "customType": "regex",
+      "fileMatch": "^.github/workflows/validate.yml$",
+      "matchStrings": [
+        "LINT_VERSION:\\s+(?<currentValue>.+)\\s*"
+      ],
+      "depNameTemplate": "golangci/golangci-lint",
+      "datasourceTemplate": "github-releases",
+      "versioningTemplate": "semver-coerced"
+    }
+  ],
+
   // Don't examine packages matching these paths
   "ignorePaths": [
     "**/vendor/**",