dependabot: group and ignore config

Author: chrmarti

.github/dependabot.yml

@@ -12,5 +12,20 @@ updates:
 
   - package-ecosystem: "npm"
     directory: "/"
+    groups:
+      all:
+        patterns:
+          - "*"
+    ignore:
+      - dependency-name: "@types/node"
+        update-types: ["version-update:semver-major"] # Keep Node 18 compatibility
+      - dependency-name: "chai"
+        update-types: ["version-update:semver-major"] # chai 4 to avoid esm
+      - dependency-name: "eslint"
+        update-types: ["version-update:semver-major"] # eslint 8 for `--rulesdir`
+      - dependency-name: "rimraf"
+        update-types: ["version-update:semver-major"] # rimraf 5 for Node 18 compatibility
+      - dependency-name: "tar"
+        update-types: ["version-update:semver-major"] # tar 6 for source compatibility
     schedule:
       interval: "weekly"