text: Title: How to open doc2vec trained on an older version of gensim?
  Body: 
  I have a large number of models trained on older gensim ? I recently updated my python library, and gensim was bumped to the latest version. The problem is the Doc2Vec.load is refusing to load the older versions. Is there a compatibility mode available ? Or what's the cleanest way to load old models and save them in the new format. I am getting the following error:
  
  
  attributeError                            Traceback (most recent call last)
  Cell In[3], line 1
  ----> 1 model = Doc2Vec.load(r'Z:\process\edgar\business_doc2vec\20230731.model')
  
  File C:\Anaconda3\envs\base_small\lib\site-packages\gensim\models\doc2vec.py:815, in Doc2Vec.load(cls, *args, **kwargs)
      810 except AttributeError as ae:
      811     logger.error(
      812         "Model load error. Was model saved using code from an older Gensim version? "
      813         "Try loading older model using gensim-3.8.3, then re-saving, to restore "
      814         "compatibility with current code.")
  --> 815     raise ae
  
  File C:\Anaconda3\envs\base_small\lib\site-packages\gensim\models\doc2vec.py:809, in Doc2Vec.load(cls, *args, **kwargs)
      786 """Load a previously saved :class:`~gensim.models.doc2vec.Doc2Vec` model.
      787 
      788 Parameters
     (...)
      806 
      807 """
      808 try:
  --> 809     return super(Doc2Vec, cls).load(*args, rethrow=True, **kwargs)
      810 except AttributeError as ae:
      811     logger.error(
      812         "Model load error. Was model saved using code from an older Gensim version? "
      813         "Try loading older model using gensim-3.8.3, then re-saving, to restore "
      814         "compatibility with current code.")
  
  File C:\Anaconda3\envs\base_small\lib\site-packages\gensim\models\word2vec.py:1949, in Word2Vec.load(cls, rethrow, *args, **kwargs)
     1947 except AttributeError as ae:
     1948     if rethrow:
  -> 1949         raise ae
     1950     logger.error(
     1951         "Model load error. Was model saved using code from an older Gensim Version? "
     1952         "Try loading older model using gensim-3.8.3, then re-saving, to restore "
     1953         "compatibility with current code.")
     1954     raise ae
  
  File C:\Anaconda3\envs\base_small\lib\site-packages\gensim\models\word2vec.py:1942, in Word2Vec.load(cls, rethrow, *args, **kwargs)
     1923 """Load a previously saved :class:`~gensim.models.word2vec.Word2Vec` model.
     1924 
     1925 See Also
     (...)
     1939 
     1940 """
     1941 try:
  -> 1942     model = super(Word2Vec, cls).load(*args, **kwargs)
     1943     if not isinstance(model, Word2Vec):
     1944         rethrow = True
  
  File C:\Anaconda3\envs\base_small\lib\site-packages\gensim\utils.py:487, in SaveLoad.load(cls, fname, mmap)
      484 compress, subname = SaveLoad._adapt_by_suffix(fname)
      486 obj = unpickle(fname)
  --> 487 obj._load_specials(fname, mmap, compress, subname)
      488 obj.add_lifecycle_event("loaded", fname=fname)
      489 return obj
  
  File C:\Anaconda3\envs\base_small\lib\site-packages\gensim\models\word2vec.py:1958, in Word2Vec._load_specials(self, *args, **kwargs)
     1956 def _load_specials(self, *args, **kwargs):
     1957     """Handle special requirements of `.load()` protocol, usually up-converting older versions."""
  -> 1958     super(Word2Vec, self)._load_specials(*args, **kwargs)
     1959     # for backward compatibility, add/rearrange properties from prior versions
     1960     if not hasattr(self, 'ns_exponent'):
  
  File C:\Anaconda3\envs\base_small\lib\site-packages\gensim\utils.py:518, in SaveLoad._load_specials(self, fname, mmap, compress, subname)
      516     logger.info("loading %s recursively from %s.* with mmap=%s", attrib, cfname, mmap)
      517     with ignore_deprecation_warning():
  --> 518         getattr(self, attrib)._load_specials(cfname, mmap, compress, subname)
      520 for attrib in getattr(self, '__numpys', []):
      521     logger.info("loading %s from %s with mmap=%s", attrib, subname(fname, attrib), mmap)
  
  File C:\Anaconda3\envs\base_small\lib\site-packages\gensim\utils.py:1522, in deprecated.<locals>.decorator.<locals>.new_func1(*args, **kwargs)
     1515 @wraps(func)
     1516 def new_func1(*args, **kwargs):
     1517     warnings.warn(
     1518         fmt.format(name=func.__name__, reason=reason),
     1519         category=DeprecationWarning,
     1520         stacklevel=2
     1521     )
  -> 1522     return func(*args, **kwargs)
  
  File C:\Anaconda3\envs\base_small\lib\site-packages\gensim\models\doc2vec.py:328, in Doc2Vec.docvecs(self)
      325 @property
      326 @deprecated("The `docvecs` property has been renamed `dv`.")
      327 def docvecs(self):
  --> 328     return self.dv
  
  AttributeError: 'Doc2Vec' object has no attribute 'dv'