Remove ipykernel pin to fix qtconsole

[MialLewis]

Description of work

Purpose of work
The mslice qtconsole is currently broken. mantidproject/mslice#910

This is fixed by upgrading ipykernel to the latest version. In order to to this the pin must be removed from workbench.

ipykernel was pinned "to deal with an issue with ipykernel v6 and incompatibility with qtconsole/workbench, at present it stops workbench from loading." This is no longer the case with the latest verison of ipykernel,

Summary of work

Remove ipykernel pin.

To test:
Packages here: https://builds.mantidproject.org/job/build_packages_from_branch/
Check all tests pass
Ensure workbench loads and appears to operate correctly.
Check function of qtconsole in both workbench and in mslice interface by running some existing scripts.

Fixes mantidproject/mslice#910

Reviewer

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[SilkeSchomann]

I've checked all items in the test section. In addition, I have installed the package both as a conda package and as a windows exe. In both cases it was possible to start workbench without error messages. I could not carry out the notebook validation from the manual test instructions for core though as notebook is not available in this package.

[MialLewis]

This PR brings back the first issue mentioned here: #34134

This is because ipykernel have introduced debugpy as a dependency which conflicts with pydevd used by pycharm.

In ipykernel 6.4.0 debugpy was made an optional dependency ipython/ipykernel#767

You can therefore remove debugpy from a developer environment using conda remove --force debugpy. This removes the warning and leaves the console functional.

I imagine this is not best practice as it leaves the environment in an unresolved state, but ipykernel is currently the only dependant package on debugpy so it should be ok.

[sf1919]

@MialLewis can you raise an issue to update the Pycharm dev docs as part of maintenance? Add it to the maintenance board please

@thomashampson can you take a look at this?