Update test_osv_source.py

Author: NeilMathew-git

test/test_osv_source.py

@@ -36,3 +36,6 @@ async def test_update_ecosystems(mock_aio_run_command):
 
     osv = OSV_Source()
     await osv.update_ecosystems()
+
+    assert "python" in osv.ecosystems
+    assert "rust" not in osv.ecosystems