Build for Scala 2.13 milestone

[ennru]

Depends on:

• Support Scala 2.13.0-M5 sullis/jms-testkit#4
• Build for scala 2.13 as well akka-grpc#506 (google-cloud-pub-sub-grpc, depending on release for Scala 2.13.0-M5 scalapb/ScalaPB#540)
• scala 2.13 support slick/slick#1958
• Support for Scala 2.13.0-M5 jwt-scala/jwt-scala#115 (google-fcm, google-cloud-pub-sub)
• Scala 2.13 support hseeberger/akka-http-json#253 (ironmq)
• https://jira.mongodb.org/browse/SCALA-506 (mongodb)
• Scala 2.13 support matsluni/aws-spi-akka-http#3 (sns, sqs)

[ennru]

akka-stream will soon become available for Scala 2.13-M4.

[2m]

The aws-spi-akka-http dependency s3mock depends on Alpakka S3 in the test scope. It has come full circle. We will have to start publishing 2.13-M5 artifacts for the Alpakka connectors that are not blocked by any dependencies so others can catch up.

[matsluni]

@2m, I am the author of aws-spi-akka-http. Would it makes sense to drop s3mock for something which is not dependent on alpakka? I guess that would simplify things?!

@gabfssilva suggested @localstack.
Do you know any other alternatives?

[2m]

Most of the Alpakka connectors (S3 included) have a few Scala dependencies and are not blocked for support of Scala 2.13. So we will be releasing artifacts for those that are built with Scala 2.13 quite soon. This will unblock s3mock. However if you see a viable alternative, like localstack, then it might make things easier in the future, when subsequent Scala 2.13 releases are out.