Update README for v6 and clean up dev dependencies

package-lock.json

@@ -22,7 +22,6 @@
       "devDependencies": {
         "@eslint/js": "^10.0.1",
         "@jest/globals": "^30.4.1",
-        "@types/jest": "^30.0.0",
         "@types/node": "^26.0.0",
         "@types/semver": "^7.7.0",
         "@typescript-eslint/eslint-plugin": "^8.62.0",
@@ -2028,17 +2027,6 @@
         "@types/istanbul-lib-report": "*"
       }
     },
-    "node_modules/@types/jest": {
-      "version": "30.0.0",
-      "resolved": "https://registry.npmjs.org/@types/jest/-/jest-30.0.0.tgz",
-      "integrity": "sha512-XTYugzhuwqWjws0CVz8QpM36+T+Dz5mTEBKhNs/esGLnCIlGdRy+Dq78NRjd7ls7r8BC8ZRMOrKlkO1hU0JOwA==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "expect": "^30.0.0",
-        "pretty-format": "^30.0.0"
-      }
-    },
     "node_modules/@types/json-schema": {
       "version": "7.0.15",
       "resolved": "https://registry.npmjs.org/@types/json-schema/-/json-schema-7.0.15.tgz",