Add conversion for backward compatibility

lm-core/src/main/scala/sbt/librarymanagement/LibraryManagementSyntax.scala

@@ -1,5 +1,7 @@
 package sbt.librarymanagement
 
+import java.net.URI
+
 trait LibraryManagementSyntax0 {
   // See http://www.scala-lang.org/news/2.12.0#traits-compile-to-interfaces
   // Avoid defining fields (val or var, but a constant is ok – final val without result type)
@@ -35,6 +37,9 @@ trait LibraryManagementSyntax
   // java.lang.System is more important, so don't alias this one
   //  final val System = C.System
   final val Optional = C.Optional
+
+  given Conversion[(String, URI), License] with
+    def apply(x: (String, URI)): License = License(x._1, x._2)
 }
 
 object syntax extends LibraryManagementSyntax

sbt-app/src/sbt-test/dependency-management/artifact/build.sbt

@@ -11,6 +11,7 @@ ThisBuild / organization     := "com.example"
 ThisBuild / organizationName := "example"
 ThisBuild / csrCacheDirectory := (ThisBuild / baseDirectory).value / "coursier-cache"
 ThisBuild / licenses         += License.Apache2
+ThisBuild / licenses         += ("foo", uri("https://example.com/"))
 
 lazy val Dev = config("dev").extend(Compile)
   .describedAs("Dependencies required for development environments")