Update pypa/gh-action-pypi-publish to 1.12.4

Output (#917)

Update Readthedocs configuration (#916)

Speed improvements (#915)

Nested integrals (#914)

Add support for nested integrals over the same space.

Improve System (#912)

Add evaluable get (#906)

Deprecations (#913)

Fix hash of compiled functions (#911)

The hash of compiled functions is based solely on the source code. Constants
are currently added to globals of the compiled function under `c{index}`, hence
constants are not included in the hash. Furthermore, parameters of evaluables
using `evalf` via the `e{index}` instance, also added to the globals, are also
not represented in the source code. As a consequence, two compiled functions
with different constants or parameters of certain evaluables may have the same
hash. This PR fixes the problem by storing constants under `c{hash(constant)}`
and disallowing using `e{index}.evalf`.

Explicit spaces function.grad, Namespace.define_for (#910)