heads-up: PROJ_LIB is now deprecated (use PROJ_DATA instead)

[jmckenna]

• PROJ_LIB will now be deprecated, and PROJ_DATA should be used instead
• see PROJ changes at ​https://github.com/OSGeo/PROJ/pull/3253
• I believe some builds of PostGIS point to PROJ_LIB
• likely both PROJ_LIB and PROJ_DATA should be checked, for now (similar to how MapServer will handle this, see ​https://github.com/MapServer/MapServer/pull/6573 )
• the big change will be part of the upcoming PROJ 9.1 release, but it's good for all projects to be ready for this

[pramsey]

Did a quick code search and only found PROJ_LIB in a CI script, one time. I think it's something people use in packaging scripts maybe? The start-up environment might sometimes want to have it?

[robe]

I think that was needed in some CI when GDAL needed to know the PROJ_LIB. Since GDAL 3, which requires direct binding, that lib path I think is ignored. But anyway not a PostGIS issue.

[robe]

Agree though that is a packaging concern, So I'll move this to packaging since I think I need to make changes to the windows packaging which tries to register PROJ_LIB.