GMT error message: Failure to open virtual file

From you message I can see that you are not using the master version, so whatever caused the error is still there. To install the master version of a package we add the `#master to package name. Thst is, in this case

] add GMT#master

The GMT point-in-polygon routine is very fast but calling the GMT lib thousands of times is not. The code on master avoids that so for (multi)thousands of points it is 2 orders of magnitude faster. And hopefully avoids the error.

The failing tests on Windows are due to