Packages should not have platform packages in the dev requirements

[stof]

Packages having dev-only platform requirements are a burden for contributors as they cannot contribute if they don't satisfy that requirement.

If this platform dependency is for an optional feature (which is the only possible case, otherwise it would be a normal requirement rather than a dev one), tests should be skipped instead when the extension is missing.

[chr-hertel]

Good one! This is referring to the ext-pdo dependency in the store component? or did you catch something else?

[stof]

this is indeed about ext-pdo in the store component. I haven't checked whether other packages are also impacted.