This release was attested with the guix-attest script in commit 64e77d397e718d9733c9aca77a97433067a7f3d7 using
env FORCE_VERSION="2.6.5" GUIX_SIGS_REPO=/path/to/feather-sigs SIGNER=<fingerprint>=<username> ./contrib/guix/guix-attest
due to an issue with a mislocated SHA256SUMS.part file with the x86_64-linux-gnu.pack target.