[hotfix] Remove Java 8 in README #289

Job	Run time
Pre-compile Checks / Basic QA	10m 56s
Default (Java 11) / Compile	55m 21s
Default (Java 11) / E2E (group 1)	1h 42m 13s
Default (Java 11) / Test packaging/licensing	35m 15s
Default (Java 11) / Test (module: core)	30m 24s
Default (Java 11) / E2E (group 2)	5h 10m 13s
Default (Java 11) / Test (module: python)	32m 49s
Default (Java 11) / Test (module: table)	37m 3s
Default (Java 11) / Test (module: connect)	24m 18s
Default (Java 11) / Test (module: tests)	36m 29s
Default (Java 11) / Test (module: misc)	31m 10s
	11h 46m 11s

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