d/control: Use ${gir:Provides} for gir1.2-ical-3.0
This changes it into a versioned Provides, so that dependent packages can depend on gir1.2-icalglib-3.0 (>= 3.0.20) or similar if they have a minimum required version.
This changes it into a versioned Provides, so that dependent packages can depend on gir1.2-icalglib-3.0 (>= 3.0.20) or similar if they have a minimum required version.