docs: update minimum API level to 23 in README

This commit updates the API badge in the `README.md` file to reflect that the minimum supported API level is now 23, up from 21.

Author: nchocha-kairosliving

README.md

@@ -4,7 +4,7 @@ A customizable, modern media/document picker for Android with support for image
 
 [![Maven Central](https://img.shields.io/maven-central/v/io.github.chochanaresh/filepicker.svg)](https://search.maven.org/artifact/io.github.chochanaresh/filepicker)
 ![Build](https://github.com/ChochaNaresh/FilePicker/actions/workflows/ci.yml/badge.svg)
-[![API](https://img.shields.io/badge/API-21%2B-brightgreen.svg?style=flat)](https://android-arsenal.com/api?level=23)
+[![API](https://img.shields.io/badge/API-23%2B-brightgreen.svg?style=flat)](https://android-arsenal.com/api?level=23)
 ![Language](https://img.shields.io/badge/language-Kotlin-orange.svg)
 ![Kotlin](https://img.shields.io/badge/Kotlin-2.3.0-blue)