Update case-app_2.13 to 2.1.0-M15 (#1245)

Author: scala-steward

project/deps.sc

@@ -69,7 +69,7 @@ object Deps {
   // Force using of 2.13 - is there a better way?
   def bloopConfig      = ivy"io.github.alexarchambault.bleep:bloop-config_2.13:1.5.0-sc-1"
   def bsp4j            = ivy"ch.epfl.scala:bsp4j:2.0.0"
-  def caseApp          = ivy"com.github.alexarchambault:case-app_2.13:2.1.0-M14"
+  def caseApp          = ivy"com.github.alexarchambault:case-app_2.13:2.1.0-M15"
   def collectionCompat = ivy"org.scala-lang.modules::scala-collection-compat:2.8.1"
   // Force using of 2.13 - is there a better way?
   def coursier           = ivy"io.get-coursier:coursier_2.13:${Versions.coursier}"