src/sage/graphs/meson.build: add new file is_projective_planar_test.py

Ultimately we may not want to install these test files, but for now
the CI is complaining about it. We can decide later on.

Author: orlitzky

src/sage/graphs/meson.build

@@ -67,6 +67,7 @@ py.install_sources(
   'independent_sets.pyx',
   'isgci.py',
   'isoperimetric_inequalities.pyx',
+  'is_projective_planar_test.py',
   'line_graph.pyx',
   'lovasz_theta.py',
   'matching.py',