Bump christophwurst/nextcloud_testing from 0.3.1 to 0.5.1

Bumps [christophwurst/nextcloud_testing](https://github.com/ChristophWurst/nextcloud_testing) from 0.3.1 to 0.5.1.
- [Release notes](https://github.com/ChristophWurst/nextcloud_testing/releases)
- [Commits](https://github.com/ChristophWurst/nextcloud_testing/compare/0.3.1...0.5.1

)

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