Require JDK17 for jackson-annotations 3.0 for proper module-info.java

[cowtowncoder]

Although initially the plan was to keep jackson-annotations buildable with JDK 8 even for Jackson 3.0, it looks like this is problematic wrt creation and use of full JPMS module-info.java.
Further, since all other modules require JDK 17 anyway there's not a ton of value in keeping annotations at Java 8.
Finally: there is intent to allow use 2.x annotations with 3.x codebase in some form, so Java 8 users can do that.

[cowtowncoder]

@clivinn-shla81092 WTH?

[cowwoc]

@cowtowncoder With JDK 25 (LTE) expected out this year, it might be worth considering requiring JDK 21 as the minimum version.

[cowtowncoder]

@cowwoc This was discussed in detail:

FasterXML/jackson-future-ideas#73

and consensus was that JDK 17 is better for bigger ecosystem.