MDC1 fix

[astrolamb]

@Hazboun6 @AaronDJohnson @stevertaylor
fixes model_general to use MDC1 - set flag mdc1=True

[astrolamb]

@AaronDJohnson do you have a suggestion on how to fix these dependency errors?

[AaronDJohnson]

I'm not sure what is going on here. It looks like sksparse is failing to install, but nothing about it has changed since 2022.

[AaronDJohnson]

Okay. It's a problem with sksparse, but it's because Cython was updated yesterday. This needs to be fixed, but I may not have time to do it myself within the next week. A temporary fix could be to pin Cython to versions <3.0, but long term we don't want to do this.

[AaronDJohnson]

@astrolamb I've merged a temporary fix to scikit-sparse to constrain the Cython version to <3.0. I'll restart the tests in a couple of hours.

[astrolamb]

Awesome, thanks @AaronDJohnson for finding this!

[AaronDJohnson]

Now the issue is with libstempo. Basically, the changes to Cython have broken most Cython packages. I've submitted a PR to libstempo to limit the Cython version.