Update README.md

Fixed typo in line `qa = pipeline({"question-answering", model=model, tokenizer=tokenizer)` by removing leading curly bracket, so code example can be copied and pasted to run directly.

README.md

@@ -81,7 +81,7 @@ ckpt = "mrm8488/longformer-base-4096-finetuned-squadv2"
 tokenizer = AutoTokenizer.from_pretrained(ckpt)
 model = AutoModelForQuestionAnswering.from_pretrained(ckpt)
 
-qa = pipeline({"question-answering", model=model, tokenizer=tokenizer)
+qa = pipeline("question-answering", model=model, tokenizer=tokenizer)
 
 text = "Huggingface has democratized NLP. Huge thanks to Huggingface for this."
 question = "What has Huggingface done?"