Mill 0.12 support

What's Changed

• Update scalafmt-core to 3.7.6 by @scala-steward in #54
• Update scalafmt-core to 3.7.7 by @scala-steward in #55
• Update scalafmt-core to 3.7.9 by @scala-steward in #56
• Update scalafmt-core to 3.7.10 by @scala-steward in #57
• Update mill-tpolecat to 0.3.5 by @scala-steward in #60
• Update mill-scalafix to 0.3.2 by @scala-steward in #73
• Update scalafmt-core to 3.7.17 by @scala-steward in #71
• Update mill-git to 0.2.5 by @scala-steward in #51
• Update org.eclipse.jgit to 6.6.1.202309021850-r by @scala-steward in #62
• Update mill-contrib-docker, mill-main, ... to 0.10.15 by @scala-steward in #74
• Update scalafmt-core to 3.8.2 by @scala-steward in #81
• Update org.eclipse.jgit to 6.10.0.202406032230-r by @scala-steward in #80
• Update mill-scalafix to 0.4.0 by @scala-steward in #78
• Update scalafmt-core to 3.8.3 by @scala-steward in #84
• Update mill-scalafix to 0.4.1 by @scala-steward in #87
• Update mill-scalafix to 0.4.2 by @scala-steward in #90

Full Changelog: v0.2.5...v0.2.6