Update scala-xml to 2.4.0

scala-xml is built against the latest scala 2.13 standard lib, so SIP-51
kicks-in when testing old Scala versions. Since we just want code to compile
in input projects, allowUnsafeScalaLibUpgrade is fine.

Author: bjaglin

build.sbt

@@ -248,6 +248,7 @@ lazy val input = projectMatrix
     logLevel := Level.Error, // avoid flood of compiler warnings
     libraryDependencies ++= testsDependencies.value,
     coverageEnabled := false,
+    allowUnsafeScalaLibUpgrade := true,
     // mimic dependsOn(shared) but allowing binary Scala version matching
     Compile / internalDependencyClasspath ++=
       resolve(shared, Compile / exportedProducts).value

project/Dependencies.scala

@@ -23,7 +23,7 @@ object Dependencies {
   val jgitV = "5.13.3.202401111512-r"
   val metaconfigV = "0.16.0"
   val nailgunV = "0.9.1"
-  val scalaXmlV = "2.2.0"
+  val scalaXmlV = "2.4.0"
   val scalametaV = "4.13.10"
   val scalatagsV = "0.13.1"
   val scalatestV = "3.2.19"