Remove iGynePy because source code not available anymore.

For reference, here is the email sent to the extension maintainers:

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To: Guillaume Pernelle, Tina Kapur

Hi Folks,

After investigating why the factory was blocking on the checkout [1] of the "iGynePy" project, i just realized that the corresponding source code is not (publicly) available anymore.

For comparison, checking out other project using similar command works [2].

[...]

Waiting this is sorted out, the corresponding extension description file has been deleted to ensure the build of all extensions can succeed.
Let me know if you have any questions,
Thanks,
Jc


[1] git clone is blocking:
// -----------
$ git clone https://github.com/gpernelle/iGynePy.git
Cloning into 'iGynePy'...
Username for 'https://github.com':    <------ blocking here
//-----------

[2] git clone non blocking:
// -----------
$ git clone https://github.com/Slicer/Slicer-DataStore.git
Cloning into 'Slicer-DataStore'...
[...]
Resolving deltas: 100% (94/94), done.
Checking connectivity... done
// -----------

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