Update defectdojo/defectdojo-nginx Docker tag to v3

This MR contains the following updates:

Package	Type	Update	Change
defectdojo/defectdojo-nginx		major	2.31.0 -> 3.31.0
defectdojo/defectdojo-nginx	ironbank-docker	major	2.31.0 -> 3.31.0
defectdojo/defectdojo-nginx	stage	major	2.31.0 -> 3.31.0

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