chore: update dependency chai to v6

Author: renovate[bot]

package-lock.json

@@ -32,7 +32,7 @@
   "devDependencies": {
     "bpmn-js-element-templates": "^2.12.0",
     "bpmn-js-headless": "^0.1.0",
-    "chai": "^5.2.0",
+    "chai": "^6.0.0",
     "esbuild": "^0.25.5",
     "eslint": "^9.28.0",
     "eslint-plugin-bpmn-io": "^2.2.0",