[2.x] test: Migrate UpdateReportSpec to verify.BasicTestSuite (#8545)

* test: Migrate UpdateReportSpec to verify.BasicTestSuite (#8543)

Migrate UpdateReportSpec.scala from ScalaTest's AnyFlatSpec + Matchers
to verify.BasicTestSuite, following the pattern established by other
test files in the lm-core module.

Changes:
- Replace AnyFlatSpec class with BasicTestSuite object
- Remove ScalaTest Matchers dependency
- Convert 'should ... in' syntax to 'test(...)' syntax
- Use Scala 3 syntax with colon indentation
- Change === to == for assertions (BasicTestSuite style)
- Add explicit types for lazy vals
- Add 'end UpdateReportSpec' marker

Fixes #8543

* Update lm-core/src/test/scala/UpdateReportSpec.scala

---------

Co-authored-by: GlobalStar117 <GlobalStar117@users.noreply.github.com>

lm-core/src/test/scala/UpdateReportSpec.scala

@@ -2,12 +2,11 @@ package sbt.librarymanagement
 
 import java.io.File
 
-import org.scalatest.flatspec.AnyFlatSpec
-import org.scalatest.matchers.should.Matchers
+import verify.BasicTestSuite
 
-class UpdateReportSpec extends AnyFlatSpec with Matchers {
-  "UpdateReport.toString" should "have a nice toString" in {
-    assert(updateReport.toString === s"""
+object UpdateReportSpec extends BasicTestSuite:
+  test("UpdateReport.toString should have a nice toString"):
+    Predef.assert(updateReport.toString == s"""
       |Update report:
       |	Resolve time: 0 ms, Download time: 0 ms, Download size: 0 bytes
       |	compile:
@@ -17,9 +16,8 @@ class UpdateReportSpec extends AnyFlatSpec with Matchers {
       |			evicted: false
       |
       |""".stripMargin.drop(1))
-  }
 
-  lazy val updateReport =
+  lazy val updateReport: UpdateReport =
     UpdateReport(
       new File("cachedDescriptor.data"),
       Vector(configurationReport),
@@ -27,25 +25,24 @@ class UpdateReportSpec extends AnyFlatSpec with Matchers {
       Map.empty
     )
 
-  lazy val configurationReport =
+  lazy val configurationReport: ConfigurationReport =
     ConfigurationReport(
       ConfigRef("compile"),
       Vector(moduleReport),
       Vector(organizationArtifactReport)
     )
 
-  lazy val moduleReport = (
+  lazy val moduleReport: ModuleReport =
     ModuleReport(ModuleID("org", "name", "1.0"), Vector.empty, Vector.empty)
       .withPublicationDate(Some(epochCalendar))
-  )
 
-  lazy val organizationArtifactReport =
+  lazy val organizationArtifactReport: OrganizationArtifactReport =
     OrganizationArtifactReport("org", "name", Vector(moduleReport))
 
-  val epochCalendar: java.util.Calendar = {
+  val epochCalendar: java.util.Calendar =
     val utc = java.util.TimeZone.getTimeZone("UTC")
     val c = new java.util.GregorianCalendar(utc, java.util.Locale.ENGLISH)
     c.setTimeInMillis(0L)
     c
-  }
-}
+
+end UpdateReportSpec