rm snapshot and update Kotlin label (#2690)

README.md

@@ -1,8 +1,7 @@
 <a href="https://arrow-kt.io" title="Arrow website"><img src="img/logo/arrow-dark.svg" width="200" alt=""></a>
 
 [![Maven Central](https://img.shields.io/maven-central/v/io.arrow-kt/arrow-core?color=4caf50&label=latest%20release)](https://maven-badges.herokuapp.com/maven-central/io.arrow-kt/arrow-core)
-[![Latest snapshot](https://img.shields.io/badge/dynamic/xml?color=orange&label=latest%20snapshot&prefix=v&query=%2F%2Fmetadata%2Fversioning%2Flatest&url=https%3A%2F%2Foss.sonatype.org%2Fservice%2Flocal%2Frepositories%2Fsnapshots%2Fcontent%2Fio%2Farrow-kt%2Farrow-core%2Fmaven-metadata.xml)](https://oss.sonatype.org/service/local/repositories/snapshots/content/io/arrow-kt/)
-[![Kotlin version](https://img.shields.io/badge/Kotlin-1.4-blue)](https://kotlinlang.org/docs/reference/whatsnew14.html)
+[![Kotlin version](https://img.shields.io/badge/Kotlin-1.6-blue)](https://kotlinlang.org/docs/whatsnew16.html)
 
 [![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://www.apache.org/licenses/LICENSE-2.0)
 [![StackOverflow](https://img.shields.io/badge/arrow--kt-grey.svg?logo=stackoverflow)](https://stackoverflow.com/questions/tagged/arrow-kt)