Compile ktor library instrumentation for earlier kotlin version (#9661)

instrumentation/ktor/ktor-1.0/library/build.gradle.kts

@@ -28,4 +28,10 @@ tasks {
       jvmTarget = "1.8"
     }
   }
+
+  compileKotlin {
+    kotlinOptions {
+      languageVersion = "1.4"
+    }
+  }
 }

instrumentation/ktor/ktor-2.0/library/build.gradle.kts

@@ -30,4 +30,10 @@ tasks {
       jvmTarget = "1.8"
     }
   }
+
+  compileKotlin {
+    kotlinOptions {
+      languageVersion = "1.6"
+    }
+  }
 }

instrumentation/ktor/ktor-common/library/build.gradle.kts

@@ -16,4 +16,10 @@ tasks {
       jvmTarget = "1.8"
     }
   }
+
+  compileKotlin {
+    kotlinOptions {
+      languageVersion = "1.4"
+    }
+  }
 }