Update versions in README

Author: koperagen

README.md

@@ -1,6 +1,6 @@
 # Kotlin Dataframe: typesafe in-memory structured data processing for JVM
 [![JetBrains incubator project](https://jb.gg/badges/incubator.svg)](https://confluence.jetbrains.com/display/ALL/JetBrains+on+GitHub)
-[![Kotlin](https://img.shields.io/badge/kotlin-1.6.0-blue.svg?logo=kotlin)](http://kotlinlang.org)
+[![Kotlin](https://img.shields.io/badge/kotlin-1.6.20-blue.svg?logo=kotlin)](http://kotlinlang.org)
 [![Maven Central](https://img.shields.io/maven-central/v/org.jetbrains.kotlinx/dataframe?color=blue&label=Maven%20Central)](https://search.maven.org/artifact/org.jetbrains.kotlinx/dataframe)
 [![GitHub License](https://img.shields.io/badge/license-Apache%20License%202.0-blue.svg?style=flat)](http://www.apache.org/licenses/LICENSE-2.0)
 
@@ -28,7 +28,7 @@ repositories {
     mavenCentral()
 }
 dependencies {
-    implementation 'org.jetbrains.kotlinx:dataframe:0.8.0-rc-7'
+    implementation 'org.jetbrains.kotlinx:dataframe:0.8.0-rc-8'
 }
 ```
 ### Jupyter Notebook