Fix class cast exception

[bmarty]

Content

Fix issue preventing notifications to be displayed.

Motivation and context

Fixes #5955

Screenshots / GIFs

Tests

• Receive a message that should trigger a notification
• if a notification is displayed, the issue is fixed.

Tested devices

• Physical
• Emulator
• OS version(s):

Checklist

• Changes have been tested on an Android device or Android emulator with API 24
• UI change has been tested on both light and dark themes
• Accessibility has been taken into account. See https://github.com/element-hq/element-x-android/blob/develop/CONTRIBUTING.md#accessibility
• Pull request is based on the develop branch
• Pull request title will be used in the release note, it clearly define what will change for the user
• Pull request includes screenshots or videos if containing UI changes
• You've made a self review of your PR

[github-actions]

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.40%. Comparing base (b5b765e) to head (7458586).
⚠️ Report is 3 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #5958   +/-   ##
========================================
  Coverage    81.40%   81.40%           
========================================
  Files         2535     2535           
  Lines        67624    67624           
  Branches      8669     8669           
========================================
+ Hits         55049    55050    +1     
  Misses        9365     9365           
+ Partials      3210     3209    -1     

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