Add missing transformer config option

[danielroehrig]

This is needed to specify a transformer in Symfony. Otherwise, the transformer configuration option is not recognized and an error is thrown.

Description of the change

Added "transformer" to the list of config options.

Related issues

rollbar/rollbar-php-symfony-bundle#65

[bxsx]

Hey @danielroehrig and thanks for the PR 👌

I would like to merge it, but we need to make our CI happy first ;)
I'm afraid I don't have write access to the downstream, so can I have you replace tabs with spaces and add a trailing comma?

[danielroehrig]

Like this?

I always hit the close button. Please ignore my incompetence.

[bxsx]

Thanks @danielroehrig !

The branch appears to be out of sync with master. Could you merge branch master into your branch?

[danielroehrig]

I needed to have the change in an older branch. We are still on 2.1, But I can also update the master branch.

[danielroehrig]

Added a new pull request directly for master. Use that and close this one.

[bxsx]

Thanks, @danielroehrig !

I close this PR as it's a duplicate of #543 now.

I needed to have the change in an older branch. We are still on 2.1, But I can also update the master branch.

Both PRs seem to be based on the 3.0.0 version.

I'll merge #543 and backport it to the 1.x/2.x versions in separate PRs.