WheelBuilder: use python version as cache key

[tdejager]

When building wheels with a source distribution, we also need to take the the PythonVersion into account when hitting the cache. Currently, we only use the contents of the sdist.

When creating the WheelKey we should probably add this to the hash.

Pixi will also need to supply this information later.

@baszalmstra when using this in the content-hash it will not actually be the content, but I don't think we can utilize the cacache metadata in this case. We could also associate it with a specific key, WDYT?

[baszalmstra]

Yeah you'd need to add the python version as part of the key.

[baszalmstra]

Yeah in that case the Python-version needs to be part of the key. So if you would use the shahash as the key previously now it would be something along the lines of:

<sha>-<python-version>

You can of course encode anything in the key.

[tdejager]

Closed by: #159