Update wdtkVersion to v0.15.3

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
org.wikidata.wdtk:wdtk-rdf (source)	0.14.7 -> 0.15.3
org.wikidata.wdtk:wdtk-datamodel (source)	0.14.7 -> 0.15.3
org.wikidata.wdtk:wdtk-dumpfiles (source)	0.14.7 -> 0.15.3

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Release Notes

Wikidata/Wikidata-Toolkit (org.wikidata.wdtk:wdtk-rdf)

### [`v0.15.3`](https://togithub.com/Wikidata/Wikidata-Toolkit/blob/HEAD/RELEASE-NOTES.md#Version-0153) Bug fix: - Download of online dumps was fixed ([#​872](https://togithub.com/Wikidata/Wikidata-Toolkit/issues/872)) Incompatible change: - Minimum Java version changed from 8 to 11 ([#​839](https://togithub.com/Wikidata/Wikidata-Toolkit/issues/839)) Versions 0.15.0 to 0.15.2 are skipped because of publishing issues.

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