emacs: Upgrading emacs version to 29.4 to address CVE-2024-39331

All boxes should be checked before merging the PR (just tick any boxes which don't apply to this PR)

[ ] The toolchain has been rebuilt successfully (or no changes were made to it)
[ ] The toolchain/worker package manifests are up-to-date
[ ] Any updated packages successfully build (or no packages were changed)
[ ] Packages depending on static components modified in this PR (Golang, *-static subpackages, etc.) have had their Release tag incremented.
[ ] Package tests (%check section) have been verified with RUN_CHECK=y for existing SPEC files, or added to new SPEC files
[ ] All package sources are available
[ ] cgmanifest files are up-to-date and sorted (./cgmanifest.json, ./toolkit/scripts/toolchain/cgmanifest.json, .github/workflows/cgmanifest.json)
[ ] LICENSE-MAP files are up-to-date (./SPECS/LICENSES-AND-NOTICES/data/licenses.json, ./SPECS/LICENSES-AND-NOTICES/LICENSES-MAP.md, ./SPECS/LICENSES-AND-NOTICES/LICENSE-EXCEPTIONS.PHOTON)
[ ] All source files have up-to-date hashes in the *.signatures.json files
[ ] sudo make go-tidy-all and sudo make go-test-coverage pass
[ ] Documentation has been updated to match any changes to the build system
[ ] If you are adding/removing a .spec file that has multiple-versions supported, please add @microsoft/cbl-mariner-multi-package-reviewers team as reviewer (Eg. golang has 2 versions 1.18, 1.21+)
[ ] Ready to merge

What does the PR accomplish, why was it needed?

Upgrading emacs version to 29.4 to address CVE.

microsoft / azurelinux