v0.21.1

• (bridgev2) Added more features and fixed bugs.
• (hicli) Added more features and fixed bugs.
• (appservice) Removed TLS support. A reverse proxy should be used if TLS is needed.
• (format/mdext) Added goldmark extension to fix indented paragraphs when disabling indented code block parser.
• (event) Added Has method for Mentions.
• (event) Added basic support for the unstable version of polls.