[Fixbug][Hidet Script] Fix a bug that hidet script does not recognize return type

[yaoyaoding]

Fix hidet script transpiler to run recognize the following code

def test_unroll():
    from hidet.lang import printf, attrs
    from hidet.ir.dtypes import float32x8, float32
    from hidet.ir import primitives
    from hidet.lang import address, cast

    with hidet.script_module() as script_module:

        @hidet.script
        def example() -> float32x8:
            attrs.func_kind = 'cpu_internal'
            return primitives.cpu.avx_f32x8_setzero()

        @hidet.script
        def main():
            attrs.func_kind = 'cpu_kernel'

            a = example()
            a_unpacked = cast(address(a), ~float32)
            for i in range(8):
                printf("%f ", a_unpacked[i])
            printf("\n")

    func = script_module.build()
    func()

    return func

Previously, hidet can not recognize the float32x8 return type.