[Versioning] Fix doc versioning (#3175)

Author: vmoens

torchrl/__init__.py

@@ -27,7 +27,10 @@
 try:
     from .version import __version__
 except ImportError:
-    __version__ = "0.0.0+unknown"
+    try:
+        from ._version import __version__
+    except ImportError:
+        __version__ = "0.0.0+unknown"
 
 try:
     from torch.compiler import is_dynamo_compiling