Fix Cite to again properly compute the year in which GAP was released

[ThomasBreuer]

The format of GAPInfo.Date has been changed recently.
Cite had not been adjusted to this change,
thus the number of the day got inserted instead of the year.

[fingolfin]

Does this affect 4.11.1 or master (it doesn't show in the dev build for me, as then the date is set to today anyway)

[ThomasBreuer]

@fingolfin The problem affects up to now only GAP 4.11.1:

gap> Cite();
Please use one of the following samples
to cite GAP version from this installation

Text:

[GAP]  GAP  –  Groups,  Algorithms, and Programming, Version 4.11.1, The GAP
Group (02), https://www.gap-system.org.
[...]

It was not yet present in GAP 4.11.0:

gap> Cite();
Please use one of the following samples
to cite GAP version from this installation

Text:

[GAP]  GAP  –  Groups,  Algorithms, and Programming, Version 4.11.0, The GAP
Group (2020), https://www.gap-system.org.
[...]

And it cannot be observed in the dev version, due to a special handling in the code (which makes it difficult to find it in advance):

gap> Cite();
Please use one of the following samples
to cite GAP version from this installation

Text:

[GAP]  GAP  –  Groups, Algorithms, and Programming, Version 4.12dev, The GAP
Group, https://www.gap-system.org.
[...]

[fingolfin]

OK thanks for the clarification; so we also need to backport it to stable-4.11 (just in case we want to make a 4.11.2)