Drop @types/mocha dependency (#1104)

We haven't used mocha, so `@types/mocha` dependency is not necessary for
now.
(follow-up for #793)

Author: Yang-33

CONTRIBUTING.md

@@ -16,7 +16,7 @@ You can freely fork the project, clone the forked repository, and start editing.
 Here are each top-level directory explained:
 
 * `lib`: TypeScript source code. You may modify files under this directory.
-* `test`: Mocha test suites. Please add tests for modification if possible.
+* `test`: Test suites. Please add tests for modification if possible.
 * `examples`: Example projects using this SDK
 * `docs`: [VitePress](https://vitepress.dev/) markdowns for project documentation
 * `tools`: Useful tools

examples/echo-bot-esm/package-lock.json

@@ -66,7 +66,6 @@
   "devDependencies": {
     "@types/express": "5.0.0",
     "@types/finalhandler": "1.2.3",
-    "@types/mocha": "10.0.10",
     "@vitest/coverage-v8": "^2.0.0",
     "express": "4.21.2",
     "finalhandler": "1.3.1",