requirements.txt problem

```
$ python3 -m venv env

$ source env/bin/activate

$ pip --version
pip 20.3.3 from /home/.../sam/env/lib/python3.6/site-packages/pip (python 3.6)

$ pip install -r requirements.txt

ERROR: Cannot install -r requirements.txt (line 24), -r requirements.txt (line 25), -r requirements.txt (line 48), -r requirements.txt (line 50), -r requirements.txt (line 52), -r requirements.txt (line 54) and absl-py==0.11.0 because these package versions have conflicting dependencies.

The conflict is caused by:
The user requested absl-py==0.11.0
jax 0.2.6 depends on absl-py
jaxlib 0.1.57 depends on absl-py
tensorboard 2.4.0 depends on absl-py>=0.4
tensorflow 2.3.1 depends on absl-py>=0.7.0
tensorflow-datasets 4.1.0 depends on absl-py
tensorflow-metadata 0.25.0 depends on absl-py<0.11 and >=0.9

To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip attempt to solve the dependency conflict

ERROR: ResolutionImpossible: for help visit https://pip.pypa.io/en/latest/user_guide/#fixing-conflicting-dependencies

```