Fix release notes wording

- Remove 'has been removed' language since deprecated features are still available
- Use present tense for deprecation notices

Signed-off-by: Mathias L. Baumann <[email protected]>

Author: Marenz

RELEASE_NOTES.md

@@ -6,12 +6,12 @@ v1 release with authentication parameter updates and dependency version expansio
 
 ## Upgrading
 
-* The `key` parameter in the `Dispatcher` constructor is now deprecated. Use `auth_key` instead.
-* The `sign_secret` parameter is now available for authentication.
+* The `key` parameter in the `Dispatcher` constructor is deprecated. Use `auth_key` instead.
+* The `sign_secret` parameter is available for authentication.
 * Environment variables have been updated:
   * `DISPATCH_API_KEY` → `DISPATCH_API_AUTH_KEY`
-  * `DISPATCH_API_SIGN_SECRET` is now available
-* The `components` property in `DispatchInfo` is now deprecated. Use `target` instead.
+  * `DISPATCH_API_SIGN_SECRET` is available
+* The `components` property in `DispatchInfo` is deprecated. Use `target` instead.
 
 ## New Features