Instrumentation.AWSLambda: Upgrade & explicitly depend on Newtonsoft.Json

[Oberon00]

Closes #1270 (alternative to that PR).

Related to a similar change in the XRay dependency: #1092

Changes

Quoting the CHANGELOG:

• Add explicit dependency on Newtonsoft.Json, upgrading the mimimum version.

  This resolves a warning that some dependency analyzers may produce where this
  package would transitively depend on a vulnerable version of Newtonsoft.Json
  through Amazon.Lambda.APIGatewayEvents.

  This also avoids a potential issue where the instrumentation would try to call
  a Newtonsoft.Json function when no other package nor the app itself depends on
  Newtonsoft.Json, since the transitive dependency would be ignored unless using
  application were compiled against a TargetFramework older than Core 3.1.

For significant contributions please make sure you have completed the following items:

• Appropriate CHANGELOG.md updated for non-trivial changes
• [ ] Design discussion issue # N/A
• [ ] Changes in public API reviewed N/A

[utpilla]

Could you update the branch with the latest changes? It looks like maintainers wouldn't have access to do that for this branch.

[Oberon00]

I updated the branch and also changed permissions so that repository maintainers should now be able to push/update here.