ci: replace dependabot with renovate

Author: terlar

.github/dependabot.yml

@@ -0,0 +1,32 @@
+{
+  $schema: "https://docs.renovatebot.com/renovate-schema.json",
+  extends: [
+    "config:recommended",
+    "helpers:pinGitHubActionDigests",
+    ":semanticCommits",
+  ],
+  labels: [
+    "automated",
+    "dependencies",
+    "chore",
+  ],
+  vulnerabilityAlerts: {
+    enabled: true,
+  },
+  packageRules: [
+    {
+      groupName: "all dependencies",
+      groupSlug: "all",
+      matchPackageNames: ["*"],
+      separateMajorMinor: false,
+      extends: ["schedule:weekly"],
+    },
+  ],
+  lockFileMaintenance: {
+    enabled: true,
+    extends: ["schedule:weekly"],
+  },
+  nix: {
+    enabled: true,
+  },
+}