Fix specifying multiple features in test_snippets.py

Co-authored-by: Noah <33094578+coolreader18@users.noreply.github.com>

tests/test_snippets.py

@@ -138,7 +138,7 @@ class SampleTestCase(unittest.TestCase):
 
         # cargo stuff
         profile_args = [] if RUST_DEBUG else ["--release"]
-        subprocess.check_call(["cargo", "build", "--features", *RUSTPYTHON_FEATURES, *profile_args])
+        subprocess.check_call(["cargo", "build", "--features", ",".join(RUSTPYTHON_FEATURES), *profile_args])
 
     @classmethod
     def tearDownClass(cls):