Includes fixes for CVE-2020-16042, CVE-2020-26971, CVE-2020-26973,
CVE-2020-26974, CVE-2020-26978, CVE-2020-35111, CVE-2020-35112, and
CVE-2020-35113.
* 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.