the app venv are not flush on requirements change

[12rambau]

This bug is currently preventing the bfast_gpu from executing on both test and prod servers.

description of the bug

When a new requirements.txt is set in a dashboard app the following script is updating/creating the venv used to launch the app. The proble m is if one of the lib is removed as the venv environment is not flush, it is not removed from the venv. It is painless is most of the case but for c++ based libs it can become critical (GDAL, CUDA, PROJ).

In the specific case of bfast_gpu the cupylib is dependant on the CUDA version. The previous installation was thus using cupy-cuda112 but as we updated CUDA in SEPAL we now request cupy-cuda114.

If you look in the current venv in the test server, launching the following script in this ven will raise the following error:

import cupy as cp 

 CuPy may not function correctly because multiple CuPy packages are installed
 in your environment:

cupy-cuda112, cupy-cuda114

potential solution

here, instead of directly install we could do it in 2 steps:

pip freeze | xargs pip uninstall -y
pip install -r requirements.txt

[cdanielw]

Now the venv will be removed before installing requirements.