Update ammonite to 2.5.4-15-f4a8969b

[scala-steward]

Updates com.lihaoyi:ammonite from 2.5.4-14-dc4c47bc to 2.5.4-15-f4a8969b.

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 = "ammonite" } ]

Or, add this to slow down future updates of this dependency:

dependencyOverrides = [{
  pullRequests = { frequency = "@monthly" },
  dependency = { groupId = "com.lihaoyi", artifactId = "ammonite" }
}]

labels: library-update, early-semver-pre-release, semver-spec-pre-release, commit-count:1