pre-commit: apply on Python files

benchmarks/bench-switch.py

unittest/python/test_LDLT.py

unittest/python/test_LLT.py

unittest/python/test_MINRES.py

unittest/python/test_complex.py

unittest/python/test_eigen_ref.py

unittest/python/test_eigen_solver.py

unittest/python/test_geometry.py

unittest/python/test_matrix.py

unittest/python/test_return_by_ref.py

unittest/python/test_self_adjoint_eigen_solver.py

unittest/python/test_switch.py

unittest/python/test_user_type.py

unittest/python/test_version.py