Sundials deprecated `realtype` in v7.0.0

[alexander-novo]

https://github.com/LLNL/sundials/releases/tag/v7.0.0

The previously deprecated types realtype and booleantype were removed from sundials_types.h and replaced with sunrealtype and sunbooleantype. The deprecated names for these types can be used by including the header file sundials_types_deprecated.h but will be fully removed in the next major release. Functions, types and header files that were previously deprecated have also been removed.

Need to go in and change these to the new name sunbooleantype.

[pelesh]

I think we should move to SUNDIALS >= 7 dependency, I don't see a reason to stick with the older versions.

I don't think we are using realtype anywhere in the GridKit code. Since the real type is a template parameter, GridKit can use anything that is configured in SUNDIALS. However, when using multiple dependencies (Ipopt, SUNDIALS, KLU), it is users responsibility to ensure they are all built with the same real and index types.

[pelesh]

Fixed in #35.