pytket v1.5.0 release candidate 0

Extend reg comparison (#441)

* Extend reg2const predicate to more general reg2reg predicate.

* Update tests according to new predicate definition.

* Black formatting.

* Update the name to new class name.

* Update to new class name.

* Update pytket/pytket/circuit/logic_exp.py

Co-authored-by: Seyon Sivarajah <seyon.sivarajah@cambridgequantum.com>

* Update pytket/pytket/circuit/logic_exp.py

Co-authored-by: Seyon Sivarajah <seyon.sivarajah@cambridgequantum.com>

* Better docstring and remove unecessary assertions and initialiser.

* Remove unecessary ellipsis.

* Update to new name.

* Check the second argument is a constant and raise an error otherwise.

* Correct stupid syntax.

* Break long line.

* Correct condition.

* Define and use a custom exception for non constant predicate operands.

* Break long line.

* Revert to previous name to avoid name clash.

* Correct naming to avoid name clash.

* Deprecation comment.

Co-authored-by: Seyon Sivarajah <seyon.sivarajah@cambridgequantum.com>