Deprecate the fugue data backend

[maximlt]

The fugue data backend has been marked as "experimental" when it was released. Since then, I doubt it has been used much, and has become a bit of a maintenance burden (e.g. not yet compatible with Pandas 3.0). I propose deprecating it.

cc @ahuang11

[ahuang11]

Since then, I doubt it has been used much

Not 100% sure about this. Maybe the deprecation warning can mention this issue, and if it is being used, they can comment on this issue.

not yet compatible with Pandas 3.0

I could raise an issue on Fugue's GitHub, but curious if you tested it on pandas 3 yet?

Otherwise, I'm okay with the decision.

[maximlt]

Not 100% sure about this.

We'll never be 100% of anything in OSS :D At least on Github the only hits for hvplot.figue (7, in total) returned are from hvPlot's repo or forks https://github.com/search?q=%22hvplot.fugue%22&type=code

but curious if you tested it on pandas 3 yet?

Yes, and that's one of the few things that broke, I had to skip some tests.