build(deps): bump certifi from 2023.5.7 to 2023.7.22 in /images/singleuser-sample #1955

Job	Run time
lint_and_validate_rendered_templates	19s
lint_and_validate_templates_with_schema	6s
lint_and_validate_templates_with_schema (v3.5.0)	13s
lint_shell_scripts	55s
test (latest, install)	2m 59s
test (stable, install, --set hub.image.name=jupyterhub/k8s-hub-slim --set prePuller.hook.enabled=...	4m 2s
test (v1.26, install, --set hub.existingSecret=test-hub-existing-secret --set proxy.secretToken=a...	3m 7s
test (v1.25, upgrade, stable, --set proxy.secretToken=aaaa1111 --set hub.cookieSecret=bbbb2222 --...	4m 27s
test (v1.24, upgrade, dev, --set proxy.secretToken=aaaa1111 --set hub.db.type=sqlite-pvc --set si...	4m 34s
test (v1.23, upgrade, 1.2.0, --set proxy.secretToken=aaaa1111 --set hub.cookieSecret=bbbb2222 --s...	4m 31s
	25m 13s

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