specifying identical_times=true for FisherModelParametrized does not change shape of times

[jonaspleyer]

Modify one of the existing tests to recreate the problem. (commit 48ed7df)
test/solving/test_convergence.py
The test has to be modified in the following way:

def test_ode_rhs_exact_solution_identical_times(self):
    self.fsmp.identical_times=True
    self.test_ode_rhs_exact_solution()
    self.fsmp.identical_times=False