Make Scala versions more consistent

Somehow the release plugin got confused about 2.12.12 (the default for
this sbt version) and 2.12.10 (the one specified for this
ssl-config-core).

build.sbt

@@ -2,11 +2,7 @@ import com.typesafe.sbt.osgi.SbtOsgi
 import com.typesafe.sbt.osgi.SbtOsgi.autoImport._
 import com.typesafe.tools.mima.core._
 
-val commonSettings = Seq(
-  scalaVersion := Version.scala212,
-  crossScalaVersions := Seq(Version.scala213, Version.scala212, Version.scala211),
-  javacOptions ++= Seq("-source", "1.8", "-target", "1.8")
-)
+ThisBuild / scalaVersion := Version.scala212
 
 val disablePublishingSettings = Seq(
   // https://github.com/sbt/sbt/pull/3380
@@ -16,10 +12,11 @@ val disablePublishingSettings = Seq(
  )
 
 lazy val sslConfigCore = project.in(file("ssl-config-core"))
-  .settings(commonSettings: _*)
   .settings(AutomaticModuleName.settings("ssl.config.core"))
   .settings(osgiSettings: _*)
   .settings(
+    crossScalaVersions := Seq(Version.scala213, Version.scala212, Version.scala211),
+    javacOptions ++= Seq("-source", "1.8", "-target", "1.8"),
     name := "ssl-config-core",
     mimaReportSignatureProblems := true,
     mimaPreviousArtifacts ++= (((CrossVersion.partialVersion(scalaVersion.value) match {