Includes fixes for CVE-2019-20503, CVE-2020-6805, CVE-2020-6806, CVE-2020-6807, CVE-2020-6811, CVE-2020-6812, and CVE-2020-6814. * gnu/packages/gnuzilla.scm (%icecat-version, %icecat-build-id): Update. (icecat-source): Update gnuzilla commit, base version, and hashes. * gnu/packages/patches/icecat-makeicecat.patch: Adapt to new version.