Move to Java 11

[vertigo17]

Move the project to Java 11 compilation.
Today it compile anfd runs fine in Java 11 but pom still point to Java 8.

[MorganLmd]

https://winterbe.com/posts/2018/08/29/migrate-maven-projects-to-java-11-jigsaw/

[vertigo17]

Will wait until confirmation from Redoute that 11 is nice to proceed.

[vertigo17]

As a reference and for debug purpose:

49 = Java 5
50 = Java 6
51 = Java 7
52 = Java 8
53 = Java 9
54 = Java 10
55 = Java 11
56 = Java 12
57 = Java 13
58 = Java 14
59 = Java 15
60 = Java 16
61 = Java 17
62 = Java 18
63 = Java 19
64 = Java 20
65 = Java 21

in case you get:
Caused by: java.lang.UnsupportedClassVersionError: org/cerberus/core/config/CerberusConfiguration has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0 (unable to load class [org.cerberus.core.config.CerberusConfiguration])

That means that commilation was made with java 11 and runtime is in java 8.