Bump ch.qos.logback:logback-classic from 1.5.20 to 1.5.21 in /e2e-tests #2033

Job	Run time
Spotbugs	1m 10s
Checkstyle	52s
Unit Tests	1m 0s
Integration Tests	9m 0s
End-to-End Testing	3m 49s
Build & Publish Docker Images (gpc-api-mock, gp2gp-gpc-api-mock, ./docker/gpc-api-mock)	22s
Build & Publish Docker Images (gpcc-mock, gp2gp-gpcc-mock, ./docker/gpcc-mock)	25s
Build & Publish Docker Images (service, gp2gp, .)	1m 36s
Build & Publish Docker Images (sds-api-mock, gp2gp-sds-api-mock, ./docker/sds-api-mock)	23s
Build & Publish Docker Images (wiremock, gp2gp-wiremock, .)	47s
Build & Publish Docker Images (mock-mhs-adaptor, gp2gp-mock-mhs, .)	1m 2s
	20m 26s

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