Configure jvmToolchain in the kotlin extension scope

Otherwise, the latest Kotlin Gradle Plugin (2.0) fails with:
"Configuring JVM toolchain in the Kotlin target level DSL is prohibited. JVM toolchain feature should be configured in the extension scope as it affects all JVM targets (JVM, Android)."

Author: Abduqodiri Qurbonzoda

integration/src/test/resources/templates/kmp-with-toolchain/build.gradle

@@ -1,7 +1,6 @@
 kotlin {
-    jvm {
-        jvmToolchain(21)
-    }
+    jvmToolchain(21)
+    jvm {}
 
     sourceSets {
         commonMain {