Update upickle to 2.0.0

[scala-steward]

Updates com.lihaoyi:upickle from 1.6.0 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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Files still referring to the old version number

The following files still refer to the old version number (1.6.0).
You might want to review and update them manually.

readme.adoc

Adjust future updates

Add this to your .scala-steward.conf file to ignore future updates of this dependency:

updates.ignore = [ { groupId = "com.lihaoyi", artifactId = "upickle" } ]

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

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

labels: library-update, early-semver-major, semver-spec-major, old-version-remains, commit-count:1

[lefou]

@lihaoyi Is it safe to bump this? Meaning, can a project switch from Mill 0.10.0 to main (0.10.x) and back without build issues caused by upickle format changes?

[lihaoyi]

@lefou my understanding is we invalidate all caches aggressively on any classpath change, so this should be safe. Caches will be busted, but no different from any other Mill code change

[lefou]

@lihaoyi Thanks. Looks like it's safe enough, then.

[lolgab]

I'm observing a regression after this update.
Everytime I restart the server all the build files get recompiled from scratch even if they were not touched at all.
Can it be because Ammonite depends on upickle 1.6.0 while Mill uses 2.0.0 ?