chore: add Renovate dependency management config (#4)

Adds renovate.json matching the standard config used across other
Privileged Escalation plugin repos (polaris, intel-gpu, rook, etc.).

Configures recommended presets, weekend schedule, and groups minor/patch
updates for npm and GitHub Actions.

Ref: PRI-128

Co-authored-by: gandalf-the-greybeard[bot] <gandalf-the-greybeard[bot]@users.noreply.github.com>
Co-authored-by: Paperclip <noreply@paperclip.ing>

renovate.json

@@ -0,0 +1,19 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": ["config:recommended"],
+  "baseBranches": ["main"],
+  "schedule": ["every weekend"],
+  "prConcurrentLimit": 10,
+  "packageRules": [
+    {
+      "matchManagers": ["npm"],
+      "matchUpdateTypes": ["minor", "patch"],
+      "groupName": "npm minor and patch"
+    },
+    {
+      "matchManagers": ["github-actions"],
+      "matchUpdateTypes": ["minor", "patch"],
+      "groupName": "github-actions minor and patch"
+    }
+  ]
+}