Release kMXKAccountAPNSActivityDidChangeNotification observer when de…

[NicolasBuquet]

Remove registered observer kMXKAccountAPNSActivityDidChangeNotification in dealloc of SettingsViewController.

Pull Request Checklist

• [X] I read the contributing guide
• [ ] UI change has been tested on both light and dark themes, in portrait and landscape orientations and on iPhone and iPad simulators
• [ ] Accessibility has been taken into account.
• [X] Pull request is based on the develop branch
• [X] Pull request contains a changelog file in ./changelog.d
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[codecov[bot]]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (94dc313) 11.86% compared to head (d50b82a) 12.37%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #7697 +/- ## =========================================== + Coverage 11.86% 12.37% +0.50% =========================================== Files 1650 1650 Lines 163863 163869 +6 Branches 67219 67267 +48 =========================================== + Hits 19446 20277 +831 + Misses 143777 142927 -850 - Partials 640 665 +25 ``` | [Flag](https://app.codecov.io/gh/vector-im/element-ios/pull/7697/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vector-im) | Coverage Δ | | |---|---|---| | [uitests](https://app.codecov.io/gh/vector-im/element-ios/pull/7697/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vector-im) | `54.97% <ø> (ø)` | | | [unittests](https://app.codecov.io/gh/vector-im/element-ios/pull/7697/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vector-im) | `6.22% <0.00%> (+0.50%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vector-im#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files](https://app.codecov.io/gh/vector-im/element-ios/pull/7697?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vector-im) | Coverage Δ | | |---|---|---| | [Riot/Modules/Settings/SettingsViewController.m](https://app.codecov.io/gh/vector-im/element-ios/pull/7697?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vector-im#diff-UmlvdC9Nb2R1bGVzL1NldHRpbmdzL1NldHRpbmdzVmlld0NvbnRyb2xsZXIubQ==) | `0.00% <0.00%> (ø)` | | ... and [29 files with indirect coverage changes](https://app.codecov.io/gh/vector-im/element-ios/pull/7697/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vector-im)

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