Release (v0.3.0)

Changes in this minor release:

• Update Dr.Jit Core (various performance and stability improvements)
• Allow functions in dr.wrap_adto return nested data structures 2d4910
• Fix matrix stride computation c7451c
• Fix dr.tile and dr.repeat for Bool types c15a71
• Support list/dict arguments in dr.wrap_ad 9f711c
• Add 3D variant for dr::meshgrid in C++ ed3d046
• Fix dr.unravel for Tensor inputs 578b0dd
• Add dr::suspend_grad and dr::resume_grad C++ routines 112c294
• Various Python type information (stub generation) improvements b102b3c