update tf version in badge

README.md

@@ -3,7 +3,7 @@
 <a href="https://github.com/openagi/datum/actions?query=workflow%3Adatum_py310"><img alt="Datum Build Status" src="https://github.com/openagi/datum/workflows/datum_py310/badge.svg"></a>
 <a href="https://github.com/openagi/datum/actions?query=workflow%3Adatum_py311"><img alt="Datum Build Status" src="https://github.com/openagi/datum/workflows/datum_py311/badge.svg"></a>
 [![PyPI version](https://badge.fury.io/py/datum.svg)](https://badge.fury.io/py/datum)
-[![TensorFlow 2.9](https://img.shields.io/badge/TensorFlow-2.9-FF6F00?logo=tensorflow)](https://github.com/tensorflow/tensorflow/releases/tag/v2.9.1)
+[![TensorFlow 2.15](https://img.shields.io/badge/TensorFlow-2.15-FF6F00?logo=tensorflow)](https://github.com/tensorflow/tensorflow/releases/tag/v2.15.0)
 [![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
 
 Datum provides APIs to create tfrecord daatsets and read tfrecord as `tf.data.Datasets`