Running example code from the README doesn't work

[rdaems]

If I run

from diffeqpy import de
def f(u,p,t):
    return -u
u0 = 0.5
tspan = (0., 1.)
prob = de.ODEProblem(f, u0, tspan)
integrator = de.init(prob, de.Tsit5())
de.step_b(integrator)

I get the following error:

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Input In [29], in <cell line: 7>()
      5 tspan = (0., 1.)
      6 prob = de.ODEProblem(f, u0, tspan)
----> 7 integrator = de.init(prob, de.Tsit5())
      8 de.step_b(integrator)

File ~/research/ideas/.venv/lib/python3.8/site-packages/julia/core.py:176, in JuliaModule.__getattr__(self, name)
    174 def __getattr__(self, name):
    175     try:
--> 176         return self.__try_getattr(name)
    177     except AttributeError:
    178         if name.endswith("_b"):

File ~/research/ideas/.venv/lib/python3.8/site-packages/julia/core.py:199, in JuliaModule.__try_getattr(self, name)
    196 if self._julia._isdefined(jl_module, name):
    197     return self._julia.eval(jl_fullname)
--> 199 raise AttributeError(name)

AttributeError: Tsit5

[ChrisRackauckas]

Fixed by new PythonCall backend.