Scala 3 support kamon 2.5.7

[vaslabs]

Summary

• Updated kamon to 2.5.7 to pull scala 3 support in kamon-instrumentation-common

Notes on http4s

• http4s 0.22 is EOL but it's not my place to remove the module but there are no scala 3 builds for it.
• http4s 1.0 is on milestone version and has scala 3 builds - updated to the latest milestone
• http4s 0.23 is the stable version

Test changes

Kamon testkit

Since kamon 2.3 release a change in the tests (and the way kamon is initialised in core) were causing kamon-http4s tests to yield failures, however testkit functionality was provided to initialise kamon - necessary changes were made here

Scalatest

Scalatest was also updated since the umbrella project has a scalatest version that has no scala 3 builds.

Scala 3 compiler

• Added the proper scala 3 flag for generating java 8 bytecode
• Added scala 3 migration flag (not actually needed but to keep it consistent with the kamon project just for future consideration)

Suggestions

• Probably some of these compiler + version updates can go to the umbrella project.
• Can probably drop http4s 0.22 as it's EOL

README update

Please let me know if you want me to update the README. Assuming we know the future version (e.g. 2.3.0) we can do

kamon	kamon-http4s	status	jdk	scala	http4s
2.5.7+	2.3.0	stable	8+	2.12, 2.13	0.22.x
2.5.7+	2.3.0	stable	8+	2.12, 2.13, 3.x	0.23.x
2.2.7+	2.3.0	stable	8+	2.12, 2.13, 3.x	1.0.x

[ivantopo]

Hey @vaslabs, thanks for bringing this up!

[vaslabs]

this file (.bsp/sbt.json) should probably be removed from version control

[Ali-Mahmood]

@vaslabs are we going to merge this one day?