v0.2.1

Changed

• Minimum supported Qiskit version is now 2.5.2, up from 1.2.0. Qiskit
  2.1.0 to 2.5.1 simplify parameter expressions incorrectly and silently return
  wrong values and gradients, for example x0**2 + x1**2 evaluates as
  (x0 + x1)**2, 2*x0 - 2/x0 as 0, and the derivative of cos(x0)**2
  misses the chain rule. Qiskit 2.5.2 fixes these. Qiskit 1.x and 2.0 are no
  longer supported.
• The qiskit-full and all extras now require qiskit-aer>=0.17.0 and
  qiskit-ibm-runtime>=0.37.0, the first releases that support Qiskit 2.
• Minimum SymPy version is now 1.12.1, up from 1.8. Older SymPy releases
  cannot convert NumPy 2 scalars, which breaks the Pauli propagation backend, and
  SymPy 1.8 does not import on Python 3.12 or later.
• Minimum PennyLane version is now 0.42.3, up from 0.34.0. Earlier releases
  do not cap autoray, and a fresh install pulls an autoray they cannot import.