Bump to 2.0.0-preview9

TLDR

• Added user-token in activity context
• For app-graph, use tenant-specific tokens to make graph calls
• Fixed ATK issues related to multi-tenant deprecation
• Fixed bot-builder adapter which broke in the last release

What's Changed

• Bump to preview 8 by @heyitsaamir in #278
• Send group Oauth requests to personal scope by @heyitsaamir in #281
• add user token in activity context by @heyitsaamir in #284
• Use tenant-specific app-token for app-graph by @heyitsaamir in #283
• Fixed streaming bug in stream.ts by @teddyam in #285
• Fix bot builder plugin so it receives messages by @heyitsaamir in #290
• Fix bicep files now that multi-tenant is no longer permitted by @heyitsaamir in #292
• Add optional conversation ref parameter to send and fix tenant app graph token during app.process by @heyitsaamir in #291

New Contributors

• @teddyam made their first contribution in #285

Full Changelog: https://github.com/microsoft/teams.ts/compare/@microsoft/[email protected]...@microsoft/[email protected]