Change feature dtype to string

ar_cov19.py

@@ -89,7 +89,7 @@ class ArCov19(datasets.GeneratorBasedBuilder):
 
         features = {}
 
-        features["tweetID"] = datasets.Value("int64")
+        features["tweetID"] = datasets.Value("string")
 
         return datasets.DatasetInfo(
             # This is the description that will appear on the datasets page.