See https://www.thunderbird.net/en-US/thunderbird/78.8.0/releasenotes/ Fixes https://www.mozilla.org/en-US/security/advisories/mfsa2021-09/ drop Cargo.toml patch for rust 1.50, was merged upstream in https://hg.mozilla.org/releases/mozilla-esr78/rev/0e8f444683cb