ci: fix unmanaged_dependency_check module install #17751

Job	Run time
root-pom	1m 47s
package_name_check	1m 9s
gapic-bom	1m 47s
gitignore_correctness	1m 8s
owlbot-py	1m 15s
group_id_check_for_maps_libraries	8m 20s
generate-readme	1m 12s
owlbot-yaml	1m 7s
	17m 45s

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