Bring the JEP 411 warnings up to date

As of Java 23, the necessary mechanisms have not yet
been disabled. (There is probably, though, with increasing
versions, an increasing risk of Java internals that lack
doPrivileged and will end up needing to leak into policy.)

pljava-so/src/main/c/Backend.c

@@ -1942,7 +1942,7 @@ void Backend_warnJEP411(bool isCommit)
 			"Those changes will come in releases after Java 17."),
 		errhint(
 			"For migration planning, this version of PL/Java can still "
-			"enforce policy in Java versions up to and including 22, "
+			"enforce policy in Java versions up to and including 23, "
 			"and Java 17 and 21 are positioned as long-term support releases. "
 			"For details on how PL/Java will adapt, please bookmark "
 			"https://github.com/tada/pljava/wiki/JEP-411")

src/site/markdown/use/policy.md

@@ -373,7 +373,7 @@ release, so relying on it is not recommended.
 The developers of Java have elected to phase out important language features
 used by PL/Java to enforce policy. The changes will come in releases after
 Java 17. For migration planning, this version of PL/Java can still enable
-policy enforcement in Java versions up to and including 22, and Java 17 and 21
+policy enforcement in Java versions up to and including 23, and Java 17 and 21
 are positioned as long-term support releases. (There is a likelihood,
 increasing with later Java versions, even before policy stops being enforceable,
 that some internal privileged operations by Java itself, or other libraries,