Linux 6.15 compat: META

Update the META file to reflect compatibility with the 6.15
kernel.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Tony Hutter <[email protected]>
Closes #17393

Author: tonyhutter

META

@@ -6,5 +6,5 @@ Release:       1
 Release-Tags:  relext
 License:       CDDL
 Author:        OpenZFS
-Linux-Maximum: 6.14
+Linux-Maximum: 6.15
 Linux-Minimum: 4.18