Includes fixes for CVE-2021-23961, CVE-2021-23994, CVE-2021-23995, CVE-2021-23998, CVE-2021-23999, CVE-2021-24002, CVE-2021-29945, and CVE-2021-29946. * gnu/packages/gnuzilla.scm (%icecat-version, %icecat-build-id): Update. (icecat-source): Update upstream source hash.