Nextcloud Dev: Re-enable it

This re-enables Nextcloud dev version. We now stick to commit hashes for library. Thus building should now work again. (I verified it locally)

Please make sure your repo is public and your branch is not protected. See https://docs.gitlab.com/ee/user/project/protected_branches.html. We enable fast-forward merges by default. If your branch is protected, we can't rebase it before merge it.

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Please remove above lines!

Required

• The app complies with the inclusion criteria
• All related fdroiddata and RFP issues have been referenced in this merge request
• Builds with fdroid build

Strongly Recommended

• The upstream app source code repo contains the app metadata (summary/description/images/changelog/etc) in a Fastlane or Triple-T folder structure
• Releases are tagged

Suggested

• External repos are added as git submodules instead of srclibs
• Multiple apks for native code

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Closes fdroiddata#