[CI] Bump MACOSX_DEPLOYMENT_TARGET to 14

[rok]

Describe the enhancement requested

We recently noticed we mostly set MACOSX_DEPLOYMENT_TARGET=12, while according to https://endoflife.date/macos 14 is the oldest currently supported version.

Component(s)

Continuous Integration

[rok]

Similar PR from 2024 #43137

[rok]

Also related #48414

[Alvaro-Kothe]

From the discussion in #49176, the arrow R library is being built on macOS 13. So maybe we should set 13 for the value of this flag instead?

[rok]

Thanks for the info @Alvaro-Kothe ! Let's stick witch CRAN limitation when we bump.