GH actions: macOS workflow needs gdal, even after loading R package cache

[florisvdh]

Bummer: the hack of PR #125 does not always work. No idea why it worked here, and not here.

* installing *source* package ‘n2khab’ ...
** using staged installation
** R
** inst
** byte-compile and prepare package for lazy loading
Error in dyn.load(file, DLLpath = DLLpath, ...) : 
  unable to load shared object '/Users/runner/work/_temp/Library/sf/libs/sf.so':
  dlopen(/Users/runner/work/_temp/Library/sf/libs/sf.so, 6): Library not loaded: /usr/local/opt/proj/lib/libproj.19.dylib
  Referenced from: /Users/runner/work/_temp/Library/sf/libs/sf.so
  Reason: image not found

So PR #125 needs to be reverted. Will happen ASAP.

[florisvdh]

Solved by PR #127.