Fix type of force_upcast to bool

[BerndDoser]

What does this PR do?

Corrects the type specification of argument force_upcast in AutoencodeKL by changing it from float to bool.

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[a-r-r-o-w]

Thanks!

[HuggingFaceDocBuilderDev]

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[a-r-r-o-w]

Failing test is unrelated