build: bump Org dep to 9.6 to match unguarded org-fold-* calls

org-drill calls org-fold-show-entry and org-fold-show-subtree from
seven sites without fboundp guards.  Both functions arrived in Org
9.6.  But the package declared org 9.3 (Package-Requires) /
org 9.2 (Cask), so users on older Org would silently void-function
at runtime instead of getting a clear install-time mismatch error.

Bumped both declarations to org 9.6.  Wrapping each of the seven
call sites with fboundp would be the alternative, but Org 9.6 was
released October 2022 — three-and-a-half years ago — and we already
have a follow-up TODO to drop the legacy time-to-inactive fallback
that this version bump unblocks.

Two tests verify the declared dep and that the org-fold APIs are
actually bound on the running Org version.

1 files changed, 1 insertions, 1 deletions

diff --git a/Cask b/Cask
index 5da2b9a..7192f02 100644
--- a/Cask
+++ b/Cask
@@ -10,5 +10,5 @@
  (depends-on "undercover")
  (depends-on "package-lint")
  (depends-on "elisp-lint"))
-(depends-on "org" "9.2")
+(depends-on "org" "9.6")