Refactored supported versions in README [no ci]

Author: andreped

README.md

@@ -11,7 +11,7 @@
 
 **GradientAccumulator** was developed by SINTEF Health due to the lack of an easy-to-use method for gradient accumulation in TensorFlow 2.
 
-The package is available on PyPI and is compatible with and have been tested against `TF >= 2.2` and `Python >= 3.6` (tested with `3.6-3.12`), and works cross-platform (Ubuntu, Windows, macOS).
+The package is available on PyPI and is compatible with and have been tested against `TF 2.2-2.12` and `Python 3.6-3.12`, and works cross-platform (Ubuntu, Windows, macOS).
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