deps: update agentkeepalive requirement from ^4.1.3 to ^4.2.0

Updates the requirements on [agentkeepalive](https://github.com/node-modules/agentkeepalive) to permit the latest version.
- [Release notes](https://github.com/node-modules/agentkeepalive/releases)
- [Changelog](https://github.com/node-modules/agentkeepalive/blob/master/History.md)
- [Commits](node-modules/agentkeepalive@4.1.3...4.2.0)

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

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

package.json

@@ -33,7 +33,7 @@
   "author": "GitHub Inc.",
   "license": "ISC",
   "dependencies": {
-    "agentkeepalive": "^4.1.3",
+    "agentkeepalive": "^4.2.0",
     "cacache": "^15.3.0",
     "http-cache-semantics": "^4.1.0",
     "http-proxy-agent": "^5.0.0",