Set Cython language level for _geoslib extension

Author: molinav

CHANGELOG.md

@@ -21,6 +21,7 @@ since version 1.3.0.
 - Fix wrong marker for `unittest2` in development requirements.
 - Fix `sdist` so that packages can be built from source distributions
   (PR [#532] by @DWesl).
+- Specify Cython language level for `_geoslib` extension explicitly.
 
 ### Removed
 - Remove deprecation notices (issue [#527]).

packages/basemap/setup.py

@@ -135,6 +135,10 @@ def run(self):
             runtime_library_dirs,
     }),
 ]
+for ext in ext_modules:
+    ext.cython_directives = [
+        ("language_level", str(sys.version_info[0])),
+    ]
 
 # Define all the different requirements.
 setup_requires = get_content("requirements-setup.txt", splitlines=True)