v0.3.15

• CubicSpline now supports bc_type="periodic".
• Adds PPoly.solve and PPoly.roots. Since output shapes must be
  static, these take a size argument for the number of roots to return and a
  fill_value for padding when fewer roots exist.
• fft_interp2d now raises an error if only one of sx, sy is given.
• Importing interpax no longer initializes the JAX backend.
• The axis keyword now works for interp1d, interp2d,
  interp3d and the Interpolator1D/2D/3D classes. For 2D
  and 3D it is a tuple giving the axes of f corresponding to each coordinate.
• Fix Interpolator1D/2D/3D with period giving different results
  from interp1d/2d/3d. Derivatives for periodic data are now approximated
  using the wrapped neighbors of every knot, so all copies of a knot share the same
  derivative.
• Bump minimum JAX version to 0.5.0