Prepare for release of version 2.0.0.dev103 (#822)

Co-authored-by: hikari-bot <90276125+hikari-bot[bot]@users.noreply.github.com>

Author: hikari-bot[bot]

CHANGELOG.md

@@ -6,6 +6,47 @@ This file is updated every release with the use of `towncrier` from the fragment
 
 .. towncrier release notes start
 
+Hikari 2.0.0.dev103 (2021-10-06)
+================================
+
+Breaking Changes
+----------------
+
+- `USE_PUBLIC_THREADS` and `USE_PRIVATE_THREADS` permissions have been removed in favour of new threads permission
+  - New permissions are split into `CREATE_PUBLIC_THREADS`, `CREATE_PRIVATE_THREADS` and `SEND_MESSAGES_IN_THREADS` ([#799](https://github.com/hikari-py/hikari/issues/799))
+- `GuildAvailableEvent` will no longer fire when the bot joins new guilds
+  - Some `guild_create`-ish methods were renamed to `guild_available` ([#809](https://github.com/hikari-py/hikari/issues/809))
+- Remove `hikari.errors.RESTErrorCode` enum
+  - The message that is sent with the error code is the info that the enum contained ([#816](https://github.com/hikari-py/hikari/issues/816))
+- PermissionOverwrite doesn't inherit from Unique anymore and isn't hashable. Equality checks now consider all its fields. ([#820](https://github.com/hikari-py/hikari/issues/820))
+
+
+Features
+--------
+
+- Add new `START_EMBEDDED_ACTIVITIES` permission ([#798](https://github.com/hikari-py/hikari/issues/798))
+- Support new `channel_types` field in `CommandOption` ([#800](https://github.com/hikari-py/hikari/issues/800))
+- Add the `add_component` method to `hikari.api.special_endpoints.ActionRowBuilder` ([#804](https://github.com/hikari-py/hikari/issues/804))
+- Add `old_guild` attribute to `GuildLeaveEvent`. ([#806](https://github.com/hikari-py/hikari/issues/806))
+- Add `GuildJoinEvent` that will fire when the bot joins new guilds ([#809](https://github.com/hikari-py/hikari/issues/809))
+
+
+Bugfixes
+--------
+
+- Fix re-uploading forms with resources ([#787](https://github.com/hikari-py/hikari/issues/787))
+- Prevent double linking embed resources, which causes them to upload twice
+  - This was caused by attempting to move the resource from one embed to another ([#788](https://github.com/hikari-py/hikari/issues/788))
+- Fix `BulkDeleteError` returning incorrect values for `messages_skipped`
+  - This affected the `__str__` and `percentage_completion`, which also returned incorrect values ([#817](https://github.com/hikari-py/hikari/issues/817))
+
+
+Documentation Improvements
+--------------------------
+
+- Add docstrings to the remaining undocumented `GatewayBot` methods ([#804](https://github.com/hikari-py/hikari/issues/804))
+
+
 Hikari 2.0.0.dev102 (2021-09-19)
 ================================