Bump mockitoVersion from 5.20.0 to 5.21.0 #564

Job	Run time
Verify / setup-maven-version	2s
Verify / ubuntu-latest jdk-17-zulu 4.0.0-rc-5	1m 27s
Verify / ubuntu-latest jdk-21-zulu 4.0.0-rc-5	31s
Verify / macos-latest jdk-21-zulu 4.0.0-rc-5	1m 6s
Verify / windows-latest jdk-25-zulu 4.0.0-rc-5	3m 2s
Verify / macos-latest jdk-25-zulu 4.0.0-rc-5	58s
Verify / ubuntu-latest jdk-25-zulu 4.0.0-rc-5	36s
Verify / windows-latest jdk-21-zulu 4.0.0-rc-5	3m 48s
	11m 30s

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