Update README.md to reflect kotlin 1.9.20 (GitLiveApp#462)

Reedyuk · web-flow · commit 49afe28778f1 · 2024-01-15T10:15:04.000Z
diff --git a/README.md b/README.md
@@ -70,8 +70,8 @@ The Firebase Kotlin SDK uses Kotlin serialization to read and write custom class
 
 ```groovy
 plugins {
-    kotlin("multiplatform") version "1.8.21" // or kotlin("jvm") or any other kotlin plugin
-    kotlin("plugin.serialization") version "1.8.21"
+    kotlin("multiplatform") version "1.9.20" // or kotlin("jvm") or any other kotlin plugin
+    kotlin("plugin.serialization") version "1.9.20"
 }
 ```
 

Original file line number	Diff line number	Diff line change
`@@ -70,8 +70,8 @@ The Firebase Kotlin SDK uses Kotlin serialization to read and write custom class`
`70`	`70`
`71`	`71`	```groovy
`72`	`72`	`plugins {`
`73`		`- kotlin("multiplatform") version "1.8.21" // or kotlin("jvm") or any other kotlin plugin`
`74`		`- kotlin("plugin.serialization") version "1.8.21"`
	`73`	`+ kotlin("multiplatform") version "1.9.20" // or kotlin("jvm") or any other kotlin plugin`
	`74`	`+ kotlin("plugin.serialization") version "1.9.20"`
`75`	`75`	`}`
`76`	`76`	```
`77`	`77`