msggen: Upgrade `jest` Dependency

Summary:
Upgrades `jest` to mitigate a dependency with security vulnerabilities.

Changelog:
[Internal]

Reviewed By: mhorowitz

Differential Revision: D28009549

fbshipit-source-id: ea3313a452e9e4b79d68781ffc37c26b00f26da5

ReactCommon/hermes/inspector/tools/msggen/package.json

@@ -20,7 +20,7 @@
     "@babel/preset-flow": "^7.2.0",
     "diff": "3.5.0",
     "extend": "3.0.2",
-    "jest": "^24.9.0",
+    "jest": "^26.6.3",
     "nwmatcher": "1.4.4",
     "randomatic": "3.0.0",
     "sshpk": "1.16.1",