Bump scala.version from 2.12.18 to 2.13.15 in /jvm-packages

Bumps `scala.version` from 2.12.18 to 2.13.15.

Updates `org.scala-lang:scala-compiler` from 2.12.18 to 2.13.15
- [Release notes](https://github.com/scala/scala/releases)
- [Commits](scala/scala@v2.12.18...v2.13.15)

Updates `org.scala-lang:scala-library` from 2.12.18 to 2.13.15
- [Release notes](https://github.com/scala/scala/releases)
- [Commits](scala/scala@v2.12.18...v2.13.15)

---
updated-dependencies:
- dependency-name: org.scala-lang:scala-compiler
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.scala-lang:scala-library
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

jvm-packages/pom.xml

@@ -38,7 +38,7 @@
  <spark.version>3.5.3</spark.version>
  <spark.version.gpu>3.5.1</spark.version.gpu>
  <fasterxml.jackson.version>2.15.0</fasterxml.jackson.version>
- <scala.version>2.12.18</scala.version>
+ <scala.version>2.13.15</scala.version>
  <scala.binary.version>2.12</scala.binary.version>
  <hadoop.version>3.4.0</hadoop.version>
  <maven.wagon.http.retryHandler.count>5</maven.wagon.http.retryHandler.count>