ostree: upgrade 2026.5 -> 2026.6

This release fixes a 2026.5 regression where static-delta pulls fail with
"mmap: No such device" when the BSPATCH output lives on FUSE, which breaks
Flatpak system updates. It also carries more hardening: dirtree objects
with duplicate names are rejected, static-delta superblocks are parsed as
untrusted, the OpenSSL signers check for a return value of 1, rofiles-fuse
blocks O_TRUNC opens and removexattr on hardlinked objects, and a crash on
loading a second revoked SPKI key is fixed. ostree-prepare-root now accepts
a /run/ostree directory created earlier by the initramfs.

https://github.com/ostreedev/ostree/releases/tag/v2026.6

AI-Generated: Uses Claude Code (Claude Opus 5.5)
Signed-off-by: Ricardo Salveti <ricardo.salveti@oss.qualcomm.com>
Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>

meta-oe/recipes-extended/ostree/ostree_2026.6.bb

@@ -22,7 +22,7 @@ GITHUB_BASE_URI = "https://github.com/ostreedev/ostree/releases"
 SRC_URI = "${GITHUB_BASE_URI}/download/v${PV}/libostree-${PV}.tar.xz \
            file://run-ptest \
            "
-SRC_URI[sha256sum] = "1829428ed2d982dc684211ff18525b57ea627056a68fa5b04f674f0ca6c9c19b"
+SRC_URI[sha256sum] = "164b8226aea6a0e6601036de02a5e3b62307bae25890ed557fb4e19020bd5974"
 
 S = "${UNPACKDIR}/libostree-${PV}"