Get ready for Debian 11 LTS

From https://lts-team.pages.debian.net/wiki/Development.html#switching-to-the-next-lts-release:

• Update the wiki page LTS/Using
• Send a reminder to debian-lts-announce@lists.debian.org two months before the official support for the last LTS ends.
• Contact the Teams/Publicity and draft an announcement that the old LTS release cycle has come to an end and a new one has started. Example, Example 2
• Ensure that the infrastructure is ready for the new LTS release.
• Contact the FTP team and ask them to wait four weeks with archiving the old LTS release to give users a "grace period" to update their systems.
• Contact the Stable Release Managers for coordinating the last point release (and so that they can clean up the proposed updates queues).
• Update all other relevant wiki pages especially LTS/Installing, LTS/Development, etc.
• Contact Wanna-build team to ask them to make oldstable build logs public. (e-mail)
• Create LTS/Bullseye
• Check/update/merge security-support-ended.debX in debian-security-support
  • Follow debian-security-support's README.source
  • We shouldn't just forward-port the EOL list, i.e. if the only reason to not support something is "we didn't support it in previous releases", then we should support it.
  • Also check for missing/pending EOLs announced in recent DSAs, e.g. searching for 'discontinued' in the [mail archive](https://lists.debian.org/cgi-bin/search?P=discontinued&DEFAULTOP=or&B=Gdebian-security-announce&SORT=0&HITSPERPAGE=10&xP=discontinued&xFILTERS=Gdebian-security-announce%7E-%7E%7E4294967295)
  • Request team members / sponsors opinion, e.g. EOL candidates for security-support-ended.deb10
• Update/verify the contents of data/packages/lts-do-call-me and data/packages/lts-do-not-call in the security tracker.
• Reference pending proposed-updates in data/dla-needed.txt to prevent conflicts