docs: fix py:class not found error #269

Job	Run time
Tests (3.8, pypi, postgresql10, rabbitmq, opensearch2)	1m 19s
Tests (3.8, pypi, postgresql10, rabbitmq, elasticsearch7)	1m 23s
Tests (3.8, pypi, postgresql10, redis, opensearch2)	1m 4s
Tests (3.8, pypi, postgresql10, redis, elasticsearch7)	1m 6s
Tests (3.8, pypi, postgresql13, rabbitmq, opensearch2)	1m 20s
Tests (3.8, pypi, postgresql13, rabbitmq, elasticsearch7)	1m 23s
Tests (3.8, pypi, postgresql13, redis, opensearch2)	1m 21s
Tests (3.8, pypi, postgresql13, redis, elasticsearch7)	1m 21s
Tests (3.8, pypi, mysql8, rabbitmq, opensearch2)	1m 21s
Tests (3.8, pypi, mysql8, rabbitmq, elasticsearch7)	1m 25s
Tests (3.8, pypi, mysql8, redis, opensearch2)	1m 22s
Tests (3.8, pypi, mysql8, redis, elasticsearch7)	1m 23s
Tests (3.9, pypi, postgresql10, rabbitmq, opensearch2)	1m 22s
Tests (3.9, pypi, postgresql10, rabbitmq, elasticsearch7)	1m 13s
Tests (3.9, pypi, postgresql10, redis, opensearch2)	1m 9s
Tests (3.9, pypi, postgresql10, redis, elasticsearch7)	1m 11s
Tests (3.9, pypi, postgresql13, rabbitmq, opensearch2)	1s
Tests (3.9, pypi, postgresql13, rabbitmq, elasticsearch7)	1s
Tests (3.9, pypi, postgresql13, redis, opensearch2)	1s
Tests (3.9, pypi, postgresql13, redis, elasticsearch7)	1s
Tests (3.9, pypi, mysql8, rabbitmq, opensearch2)	1m 21s
Tests (3.9, pypi, mysql8, rabbitmq, elasticsearch7)	1m 21s
Tests (3.9, pypi, mysql8, redis, opensearch2)	1m 18s
Tests (3.9, pypi, mysql8, redis, elasticsearch7)	1m 21s
	26m 8s

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