Master: Update openpolicyagent/gatekeeper Docker tag to v3.5.0

This MR contains the following updates:

Package	Type	Update	Change
openpolicyagent/gatekeeper	ironbank-docker	minor	v3.4.0 -> v3.5.0
openpolicyagent/gatekeeper		minor	v3.4.0 -> v3.5.0
openpolicyagent/gatekeeper	stage	minor	v3.4.0 -> v3.5.0

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