Fix deprecation warning when using varargs in Scala 2.13.0

[flamingelk]

Fix deprecation warning in Scala 2.13.0 when using varargs.

[lightbend-cla-validator]

At least one pull request committer is not linked to a user. See https://help.github.com/en/articles/why-are-my-commits-linked-to-the-wrong-user#commits-are-not-linked-to-any-user

[lightbend-cla-validator]

At least one pull request committer is not linked to a user. See https://help.github.com/en/articles/why-are-my-commits-linked-to-the-wrong-user#commits-are-not-linked-to-any-user

[octonato]

Fixes #237

[octonato]

Thanks @flamingelk.

LGTM, but I'm holding up the merge becasue it seems that there is an issue with the CLA. It passed the check, but at the same time it added a message saying that one of your commits can't be identified.

I need to check how to proceed with that. Alternatively, if you squash your branch and do a forced push using a user that GitHub can identify, then I think we are good.

[octonato]

@flamingelk, I checked and we are fine. Don't need to squash yourself. We will do the merge.

[mkurz]

Reminder to also port this to the master branch.

[mkurz]

@marcospereira Looks like mergify doesn't care about the needs-forwardport label in the twirl repo.

[octonato]

Added PR for forward port, removing label

[pme123]

I use Play 2.7.3 - and with that Twirl 1.4.2.

I have still deprecation warnings. see https://stackoverflow.com/questions/58058690/scala-2-13-passing-an-explicit-array-value-to-a-scala-varargs-method-is-depreca

Do I have to change something in my code?