ci: FIX tests in Linux and improve CONDA build.

* ci: Update miniconda ref.
** Replace setup nosetests --> nosetests.
** Write `conda_requirements.txt`.
* docs: CONDA & PANDAS install instructions.
* build: Add nosetests into setup.py setup-requirments.
* tests: Do not import xlwings in linux
** Rename func mistaken as TC by bare `nosetests` cmd.