Use v2 of gha-scala-library-release-workflow

https://github.com/guardian/gha-scala-library-release-workflow/releases/tag/v2.0.0

We no longer need to include `sbt-sonatype` in our project, thanks to this PR,
included in v2:

* guardian/gha-scala-library-release-workflow#62

Author: rtyley

.github/workflows/release.yml

@@ -5,7 +5,7 @@ on:
 
 jobs:
   release:
-    uses: guardian/gha-scala-library-release-workflow/.github/workflows/reusable-release.yml@v1
+    uses: guardian/gha-scala-library-release-workflow/.github/workflows/reusable-release.yml@v2
     permissions: { contents: write, pull-requests: write }
     secrets:
       SONATYPE_TOKEN: ${{ secrets.AUTOMATED_MAVEN_RELEASE_SONATYPE_TOKEN }}

project/plugins.sbt

@@ -1,5 +1,3 @@
 addSbtPlugin("com.github.sbt" % "sbt-release" % "1.4.0")
 
-addSbtPlugin("org.xerial.sbt" % "sbt-sonatype" % "3.12.2")
-
 addSbtPlugin("ch.epfl.scala" % "sbt-version-policy" % "3.2.1")