scala 2.13

[lewismj]

Hopefully, this fixes .travis file and tests.

In this PR I've added the minimal set of code changes for a Scala 2.13 build.

Since 2.13, the import 'scala.jdk.CollectionConverters' is preferred for Java <=> Scala collection conversion.

However, I thought it better to leave warning, rather than change the build (having separate code directory for Scala versions) - just for one import statement: 2.14 & 3 will use the 2.13 convention and better to just change the import statement in a future version. If you did want separate sources, I think this would be a good first step anyway.

[glibas]

Hi @lewismj , thank you for your contribution. Looks good to me. Merging.

[aslakhellesoy]

Hi @lewismj,

Thanks for your making your first contribution to Cucumber, and welcome to the Cucumber committers team! You can now push directly to this repo and all other repos under the cucumber organization! 🍾

In return for this generous offer we hope you will:

• ✅ Continue to use branches and pull requests. When someone on the core team approves a pull request (yours or someone else's), you're welcome to merge it yourself.
• 💚 Commit to setting a good example by following and upholding our code of conduct in your interactions with other collaborators and users.
• 💬 Join the community Slack channel to meet the rest of the team and make yourself at home.
• ℹ️ Don't feel obliged to help, just do what you can if you have the time and the energy.
• 🙋 Ask if you need anything. We're looking for feedback about how to make the project more welcoming, so please tell us!

On behalf of the Cucumber core team,
Aslak Hellesøy
Creator of Cucumber

[lewismj]

Hi @aslakhellesoy,

Thanks very much, I've been maintaining an SBT cucumber plugin, so would be great to delve a little deeper into cucumber itself.

[mpkorstanje]

Cheers!