BUGFIX: Prevent type hint errors with latest Fluid minor release

[Sebobo]

The 2.8.0 release of Fluid introduced breaking changes (type declarations), thus this changes the dependency to allow only 2.7.x.

Resolves: #3037

Checklist

• Code follows the PSR-2 coding style
• Tests have been created, run and adjusted as needed
• The PR is created against the lowest maintained branch
• Reviewer - PR Title is brief but complete and starts with FEATURE|TASK|BUGFIX
• Reviewer - The first section explains the change briefly for change-logs
• Reviewer - Breaking Changes are marked wit !!! and have upgrade-instructions

[kitsunet]

Thank you!

[markusguenther]

Guess we should upmerge that immediately and release it to prevent more issues.
I can take care.

[kdambekalns]

👍 A pity that's needed, though…

[Sebobo]

Why do we have that dependency in two places?

[kitsunet]

You mean root of collection and fluidadaptor? For the split packages. Technically only the Adaptor depends on fluid, but composer doesn't understand our collections so for composer if you install the collection we need to mirror all dependencies from all included packages to the top level composer.json, there is a build script to do that automatically, you should normally not change the root collection composer.json by hand.

Build/BuildEssentials/ComposerManifestMerger.php you just call this in the root of the collection.