Build(deps): Bump async from 1.5.2 to 2.6.4 in /src

Bumps [async](https://github.com/caolan/async) from 1.5.2 to 2.6.4.
- [Release notes](https://github.com/caolan/async/releases)
- [Changelog](https://github.com/caolan/async/blob/v2.6.4/CHANGELOG.md)
- [Commits](https://github.com/caolan/async/compare/v1.5.2...v2.6.4

)

---
updated-dependencies:
- dependency-name: async
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

src/package.json

@@ -10,7 +10,7 @@
   },
   "dependencies": {
     "@project-sunbird/telemetry-sdk": "0.0.24",
-    "async": "^3.2.1",
+    "async": "^2.6.4",
     "axios": "^0.19.2",
     "better-config": "^1.2.3",
     "bluebird": "^3.7.2",