Log Message:
thunderbird: Update to 78.12.0

Changelog:
Fixes:

Sending an email containing HTML links with spaces in the URL sometimes
resulted in broken links

Folder Pane display theme fixes for macOS

Chat account settings did not always save as expected

RSS feed subscriptions sometimes lost

Calendar: A parsing error for alarm triggers of type "DURATION" caused sync
problems for some users

Various security fixes

Security fixes:
#CVE-2021-29969: IMAP server responses sent by a MITM prior to STARTTLS could
 be processed
#CVE-2021-29970: Use-after-free in accessibility features of a document
#CVE-2021-30547: Out of bounds write in ANGLE
#CVE-2021-29976: Memory safety bugs fixed in Thunderbird 78.12