jupyter syntaxerror stemming from wrong version of "decorator" package

[Joaoloula]

Following the conda installation instructions leads to the package "decorator" being installed with a version that requires python3, which in turn breaks jupyter (see https://stackoverflow.com/questions/69773657/cannot-run-jupyter-notebook-by-python2-7)

This can be fixed by adding "decorator=4.4.2" to conda_probcomp.txt