Upload data files to repository and update download URLs

# Pull Request Overview
- Upload Few-NERD files to the repository in a directory called "data"
- Update the URLs to download data files from this repository

# Details
The download from the tsinghua cloud seems to be either slow or unreliable, which is why the dataset viewer on huggingface datasets was disabled. Since Few-NERD is distributed under CC BY-SA 4.0 license we can just upload the files here and use them directly.

.gitattributes

@@ -14,3 +14,6 @@
 *.pb filter=lfs diff=lfs merge=lfs -text
 *.pt filter=lfs diff=lfs merge=lfs -text
 *.pth filter=lfs diff=lfs merge=lfs -text
+data/inter.zip filter=lfs diff=lfs merge=lfs -text
+data/intra.zip filter=lfs diff=lfs merge=lfs -text
+data/supervised.zip filter=lfs diff=lfs merge=lfs -text

data/inter.zip

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:b1edeb7035f543f0b773bcce438b57198f5093ec8e656c5a2e5356f9e587e485
+size 12029124

data/intra.zip

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:7936bf060fa9f98b41b8629a6059df20b16a45d4d73ef382e53754afb30bb143
+size 11945789

data/supervised.zip

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:6b38b77701bd50b7615c299988180595c02cca4b4060777fd399039b6336f8ad
+size 14577157

few-nerd.py

@@ -23,11 +23,13 @@ other two are few-shot: Few-NERD (INTRA) and Few-NERD (INTER).
 
 _LICENSE = "CC BY-SA 4.0"
 
-# the original data files (zip of .txt) can be downloaded from tsinghua cloud
+# the original data files (zip of .txt) can be downloaded from tsinghua cloud, but we chose to host them on huggingface.co
+# for better reliability and download speed
+_URL = "https://huggingface.co/datasets/DFKI-SLT/few-nerd/resolve/main/data"
 _URLs = {
-    "supervised": "https://cloud.tsinghua.edu.cn/f/09265750ae6340429827/?dl=1",
-    "intra": "https://cloud.tsinghua.edu.cn/f/a0d3efdebddd4412b07c/?dl=1",
-    "inter": "https://cloud.tsinghua.edu.cn/f/165693d5e68b43558f9b/?dl=1",
+    "supervised": f"{_URL}/supervised.zip",
+    "intra": f"{_URL}/intra.zip",
+    "inter": f"{_URL}/inter.zip"
 }
 
 # the label ids, for coarse(NER_TAGS_DICT) and fine(FINE_NER_TAGS_DICT)