fix: remove duplicate upgrade notes (#7759)

source/upgrade/important-upgrade-notes.rst

@@ -12,10 +12,7 @@ Important Upgrade Notes
   - Mattermost plugins built with Go versions 1.22.0 and 1.22.1 do not work. Plugin developers should use Go 1.22.2 or newer instead.
   - Keybase has stopped serving our Ubuntu repository signing key. If you were using it, update your installation scripts to retrieve the key as mentioned in our docs: https://docs.mattermost.com/install/install-ubuntu.html.
   - MySQL 8.0.22 contains an `issue with JSON column types <https://bugs.mysql.com/bug.php?id=101284>`__ changing string values to integers which is preventing Mattermost from working properly. Users are advised to avoid this database version.
-  - Upgrading the Microsoft Teams Calling plugin to v2.0.0 requires users to reconnect their accounts.
   - When upgrading to 7.x from a 5.x release please make sure to upgrade to 5.37.10 first for the upgrade to complete successfully.
-  - Mattermost plugins built with Go versions 1.22.0 and 1.22.1 do not work. Plugin developers should use go 1.22.2 or newer instead.
-  - Keybase has stopped serving our Ubuntu repository signing key. If you were using it, update your installation scripts to retrieve the key as mentioned in our docs: https://docs.mattermost.com/install/install-ubuntu.html.
 
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 | If you’re upgrading                                | Then...                                                                                                                                                          |