Update sbt-ci-release to 1.12.0 (#74)

* Update sbt-ci-release to 1.12.0

* fix: pin sbt-git explicitly

sbt-ci-release 1.12.0 no longer pulls in sbt-git (sbt/sbt-ci-release#471),
but publish.sbt imports com.github.sbt.git.SbtGit. Declare sbt-git 2.1.0
directly to keep the build loading.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: John Axe <jigarkhwar88@gmail.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: 3 people

project/plugins.sbt

@@ -2,5 +2,7 @@ resolvers ++= Seq(
   "Confluent" at "https://packages.confluent.io/maven/",
 )
 
-addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.11.2")
+addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.12.0")
+// sbt-ci-release 1.12.0 dropped its sbt-git dependency (sbt/sbt-ci-release#471); publish.sbt needs it
+addSbtPlugin("com.github.sbt" % "sbt-git"        % "2.1.0")
 addSbtPlugin("org.scalameta"  % "sbt-scalafmt"   % "2.6.1")