Update utest to 0.8.1

[scala-steward]

Updates com.lihaoyi:utest from 0.7.11 to 0.8.1. 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.lihaoyi", artifactId = "utest" } ] ``` Or, add this to slow down future updates of this dependency: ``` dependencyOverrides = [{ pullRequests = { frequency = "30 days" }, dependency = { groupId = "com.lihaoyi", artifactId = "utest" } }] ```

labels: test-library-update, early-semver-major, semver-spec-minor, commit-count:1

[scala-steward]

Superseded by #236.