fix: add render_mode getter to Wrapper
diff --git a/gym/core.py b/gym/core.py
index c3d06cd8801..ffffb22000a 100644
--- a/gym/core.py
+++ b/gym/core.py
@@ -358,6 +358,11 @@ def metadata(self) -> dict:
     def metadata(self, value):
         self._metadata = value
 
+    @property
+    def render_mode(self) -> Optional[str]:
+        """Returns the environment render_mode."""
+        return self.env.render_mode
+
     @property
     def np_random(self) -> RandomNumberGenerator:
         """Returns the environment np_random."""

Currently, wrapped environments don't forward correctly the attribute `render_mode`.
This PR fixes this; thanks @Markus28 for spotting this