Update model graden readme.

PiperOrigin-RevId: 393545790

official/README.md

@@ -82,9 +82,9 @@ built from the
 as tagged branches or [downloadable releases](https://github.com/tensorflow/models/releases).
 * Model repository version numbers match the target TensorFlow release,
 such that
-[release v2.2.0](https://github.com/tensorflow/models/releases/tag/v2.2.0)
+[release v2.5.0](https://github.com/tensorflow/models/releases/tag/v2.5.0)
 are compatible with
-[TensorFlow v2.2.0](https://github.com/tensorflow/tensorflow/releases/tag/v2.2.0).
+[TensorFlow v2.5.0](https://github.com/tensorflow/tensorflow/releases/tag/v2.5.0).
 
 Please follow the below steps before running models in this repository.
 
@@ -98,6 +98,11 @@ upgrade your TensorFlow to [the latest TensorFlow 2](https://www.tensorflow.org/
 pip3 install tf-nightly
 ```
 
+* Python 3.7+
+
+Our integration tests run with Python 3.7. Although Python 3.6 should work, we
+don't recommend earlier versions.
+
 ### Installation
 
 #### Method 1: Install the TensorFlow Model Garden pip package