Update sbt-assembly to 2.0.0

[scala-steward]

Updates com.eed3si9n:sbt-assembly from 0.15.0 to 2.0.0. GitHub Release Notes - Version Diff

I'll automatically update this PR to resolve conflicts as long as you don't change it yourself.

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Adjust future updates

Add this to your `.scala-steward.conf` file to ignore future updates of this dependency: ``` updates.ignore = [ { groupId = "com.eed3si9n", artifactId = "sbt-assembly" } ] ``` Or, add this to slow down future updates of this dependency: ``` dependencyOverrides = [{ pullRequests = { frequency = "@monthly" }, dependency = { groupId = "com.eed3si9n", artifactId = "sbt-assembly" } }] ```

labels: sbt-plugin-update, early-semver-major, semver-spec-major, commit-count:1

[scala-steward]

Superseded by #101.