This change will remove the fasttext dependency from txtai.

It has caused a number of problems for a while and it's only getting worse given that fasttext is deprecated. There is fasttext-wheel which is more reliable but it's unknown how long that will be maintained and how frequently. For example, there aren't Python 3.13 builds.

For those who want to continue building fasttext models, see the staticvectors project. staticvectors has a trainer pipeline that can build a fasttext model and export it to a format that allows pure Python inference.

This task should also remove the pymagnitude-lite dependency.

Previous issues with fasttext: #423, #531, #572, #597, #639, #716, #756