Remove tf.function in gradient operator to avoid multiple useless retracings

[cofri]

The tf.function decorator on the gradient function operator was slowing down because of multiple retracings. Removing it speeds up the computation.

Adding tf.function on ODIN input_perturbation() function was the fastest option but input_perturbation() would not be framework-agnostic anymore.

As a temporary hotfix, we remove @tf.function decorator from gradient method to prevent useless raytracing. We will work on a more long-term solution in a future PR (see issue #52) .

[github-actions[bot]]

☂️ Python Coverage

current status: ✅

Overall Coverage

Lines	Covered	Coverage	Threshold	Status
1613	1453	90%	70%	🟢

New Files

No new covered files...

Modified Files

File	Coverage	Status
oodeel/utils/tf_operator.py	96%	🟢
TOTAL	96%	🟢

updated for commit: 665bb1b by action🐍