docs: Update source URL for `legislators-historical.csv` #14413

Job	Run time
check-wasm	6m 45s
integration-test (ubuntu-latest)	1m 54s
check-features	9m 40s
integration-test (windows-latest)	4m 41s
test (ubuntu-latest)	3m 42s
test (windows-latest)	10m 29s
	37m 11s

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