SequenceBaseBlock validation enforces slew rate smaller than max_slew

In current implementation max slew is not allowed.

In Line 102 at commit 8257075f the condition.

grad_slew_in_specs = np.all(grad_slew < system_specs.max_slew.m_as("mT/m/ms"))

should be changed to:

grad_slew_in_specs = np.all(grad_slew <= system_specs.max_slew.m_as("mT/m/ms"))