Update Code example according to deprecation of AutoModeWithLMHead (#7555)

'The class `AutoModelWithLMHead` is deprecated and will be removed in a future version. Please use `AutoModelForCausalLM` for causal language models, `AutoModelForMaskedLM` for masked language models and `AutoModelForSeq2SeqLM` for encoder-decoder models.'
I dont know how to change the 'How to use this model directly from the 🤗/transformers library:' part since it is not part of the model-paper

model_cards/microsoft/DialoGPT-large/README.md

@@ -31,12 +31,12 @@ ArXiv paper: [https://arxiv.org/abs/1911.00536](https://arxiv.org/abs/1911.00536
 Now we are ready to try out how the model works as a chatting partner!
 
 ```python
-from transformers import AutoModelWithLMHead, AutoTokenizer
+from transformers import AutoModelForCausalLM, AutoTokenizer
 import torch
 
 
 tokenizer = AutoTokenizer.from_pretrained("microsoft/DialoGPT-large")
-model = AutoModelWithLMHead.from_pretrained("microsoft/DialoGPT-large")
+model = AutoModelForCausalLM.from_pretrained("microsoft/DialoGPT-large")
 
 # Let's chat for 5 lines
 for step in range(5):

model_cards/microsoft/DialoGPT-medium/README.md

@@ -31,12 +31,12 @@ ArXiv paper: [https://arxiv.org/abs/1911.00536](https://arxiv.org/abs/1911.00536
 Now we are ready to try out how the model works as a chatting partner!
 
 ```python
-from transformers import AutoModelWithLMHead, AutoTokenizer
+from transformers import AutoModelForCausalLM, AutoTokenizer
 import torch
 
 
 tokenizer = AutoTokenizer.from_pretrained("microsoft/DialoGPT-medium")
-model = AutoModelWithLMHead.from_pretrained("microsoft/DialoGPT-medium")
+model = AutoModelForCausalLM.from_pretrained("microsoft/DialoGPT-medium")
 
 # Let's chat for 5 lines
 for step in range(5):

model_cards/microsoft/DialoGPT-small/README.md

@@ -31,12 +31,12 @@ ArXiv paper: [https://arxiv.org/abs/1911.00536](https://arxiv.org/abs/1911.00536
 Now we are ready to try out how the model works as a chatting partner!
 
 ```python
-from transformers import AutoModelWithLMHead, AutoTokenizer
+from transformers import AutoModelForCausalLM, AutoTokenizer
 import torch
 
 
 tokenizer = AutoTokenizer.from_pretrained("microsoft/DialoGPT-small")
-model = AutoModelWithLMHead.from_pretrained("microsoft/DialoGPT-small")
+model = AutoModelForCausalLM.from_pretrained("microsoft/DialoGPT-small")
 
 # Let's chat for 5 lines
 for step in range(5):