META: set Linux minimum version to 4.18

This sets RHEL8's base kernel[1] as the floor, and includes the oldest
kernel.org LTS (4.19).

1. https://access.redhat.com/articles/3078#RHEL8

Sponsored-by: https://despairlabs.com/sponsor/
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Tony Hutter <[email protected]>
Reviewed-by: Tino Reichardt <[email protected]>
Signed-off-by: Rob Norris <[email protected]>
Closes openzfs#16479

Author: robn

META

@@ -7,4 +7,4 @@ Release-Tags:  relext
 License:       CDDL
 Author:        OpenZFS
 Linux-Maximum: 6.10
-Linux-Minimum: 3.10
+Linux-Minimum: 4.18