chore(deps): update registry.gitlab.com/security-products/gemnasium-maven docker tag to v6

This MR contains the following updates:

Package	Type	Update	Change
registry.gitlab.com/security-products/gemnasium-maven	final	major	5 -> 6

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Release Notes

gitlab-org/security-products/analyzers/gemnasium (registry.gitlab.com/security-products/gemnasium-maven)

v6

• Major version release (!969)
• Update go module version to `gitlab.com/gitlab-org/security-products/analyzers/gemnasium/v6 (!969)

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