Revert "Created HybridToBoxWrapper to handle hybrid actions but still integrate with the library"

This reverts commit 365bdb9.

Author: AlexPasqua

sb3_contrib/common/wrappers/__init__.py

@@ -1,5 +1,4 @@
 from sb3_contrib.common.wrappers.action_masker import ActionMasker
 from sb3_contrib.common.wrappers.time_feature import TimeFeatureWrapper
-from sb3_contrib.common.wrappers.hybrid_to_box_wrapper import HybridToBoxWrapper
 
-__all__ = ["ActionMasker", "TimeFeatureWrapper", "HybridToBoxWrapper"]
+__all__ = ["ActionMasker", "TimeFeatureWrapper"]