Update jhipster/jhipster-registry Docker tag to v7

This MR contains the following updates:

Package	Type	Update	Change
jhipster/jhipster-registry	ironbank-docker	major	v6.8.0 -> v7.0.0
jhipster/jhipster-registry		major	v6.8.0 -> v7.0.0
jhipster/jhipster-registry	stage	major	v6.8.0 -> v7.0.0

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