Bump Python requirements

CMakeLists.txt

doc/sphinx/appendix.rst

doc/sphinx/inter_non-bonded.rst

doc/tutorials/langevin_dynamics/langevin_dynamics.ipynb

testsuite/python/constraint_shape_based.py

testsuite/python/integrator_langevin_stats.py

testsuite/python/interactions_bonded.py

testsuite/python/interactions_non-bonded.py

testsuite/python/lb_pressure_tensor.py

testsuite/python/p3m_madelung.py

testsuite/python/tests_common.py

testsuite/python/thermalized_bond.py

testsuite/python/thermostats_common.py

testsuite/python/widom_insertion.py