Prepare for new CCL release

[hsinfan1996]

Fix how max supported CCL version is checked to prepare for the new release.

[coveralls]

coverage: 100.0%. remained the same
when pulling 3a5f3aa on issue/619/Fix_CCL_version_checking
into 50876a8 on main.

[hsinfan1996]

Note: origin of this issue parse("3") is identical to parse("3.0.0").

[hsinfan1996]

pyccl 3.0.1 and 3.0.2 are released.

[joezuntz]

Is there a reason you're installing CCL from source? It is available in conda-forge, and much quicker to install that way!

[hsinfan1996]

Is there a reason you're installing CCL from source? It is available in conda-forge, and much quicker to install that way!

I think it is partly because we want to check the dev versions, and in the CI script, we don't need to specify what version to install.

[hsinfan1996]

conda will be broken after installing cmake due to an upstream issue libarchive/libarchive#1976, so I moved up the installation of sphinx prereqs.

[combet]

@hsinfan1996, @m-aguena - I see this morning that you've made further changes here that should work for all CCL v3.x.x, right? Thank you! Is this ready for review/to be merged?

[hsinfan1996]

@combet Yes, this is ready for review.

[combet]

Thank you! All looks good and it installed and ran happily at my end with a conda installed CCL v3.0.2.