Pin ddtrace to <v4.

[purple4reina]

What does this PR do?

Motivation

Testing Guidelines

Additional Notes

Types of Changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog
• This PR passes the integration tests (ask a Datadog member to run the tests)

[kimmoahokas]

Should this currently pin the version to <3? Taking https://github.com/DataDog/dd-trace-py/releases/tag/v3.0.0 looks like a bigger change here. Just interested because we had just a small incident where we took dd-trace-py in use in custom instrumentation, but that broke because we wrapped the function with datadog-lambda-python that requires v2.

[purple4reina]

Should this currently pin the version to <3? Taking DataDog/dd-trace-py@v3.0.0 (release) looks like a bigger change here. Just interested because we had just a small incident where we took dd-trace-py in use in custom instrumentation, but that broke because we wrapped the function with datadog-lambda-python that requires v2.

The most recent version of the datadog-lambda-python package now supports v3.0 of ddtrace. I suspect that you were using an older version of datadog-lambda-python that did not yet support v3.0 of ddtrace, which caused your incident.