Update eclipse/rdf4j-workbench Docker tag to v5.0.3

This MR contains the following updates:

Package	Type	Update	Change
eclipse/rdf4j-workbench		patch	5.0.2 -> 5.0.3
eclipse/rdf4j-workbench	ironbank-docker	patch	5.0.2 -> 5.0.3
eclipse/rdf4j-workbench	stage	patch	5.0.2 -> 5.0.3

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