Add Flower Datasets tests as GitHub workflow #2609

Job	Run time
Framework / bare	1m 59s
Framework / jax	2m 4s
Framework / pytorch	3m 20s
Framework / tensorflow	3m 48s
Framework / tabnet	3m 3s
Strategy / FedMedian	1m 23s
Framework / opacus	3m 30s
Strategy / FedTrimmedAvg	1m 20s
Framework / pytorch-lightning	3m 9s
Framework / mxnet	1m 48s
Strategy / QFedAvg	2m 3s
Strategy / FaultTolerantFedAvg	1m 20s
Framework / scikit-learn	2m 24s
Framework / fastai	5m 10s
Strategy / FedAvgM	1m 33s
Strategy / FedAdam	1m 23s
Framework / pandas	1m 41s
Strategy / FedAdagrad	1m 21s
Strategy / FedYogi	1m 27s
	43m 46s

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