Fix underscore within hashtag

tests.py

@@ -5328,6 +5328,8 @@ def _test_valid_hash_tag():
     assert valid_hash_tag('ThisIsVälid')
     assert valid_hash_tag('यहमान्यहै')
     assert valid_hash_tag('한국어')
+    assert valid_hash_tag('테스트')
+    assert valid_hash_tag('테_스트')
     assert not valid_hash_tag('this-is-invalid')
     assert not valid_hash_tag('ThisIsNotValid!')
     assert not valid_hash_tag('#ThisIsAlsoNotValid')

utils.py

@@ -1874,7 +1874,7 @@ def _is_valid_language(text: str) -> bool:
     for lang_name, lang_range in natural_languages.items():
         ok_lang = True
         for char in text:
-            if char.isdigit():
+            if char.isdigit() or char == '_':
                 continue
             if ord(char) not in range(lang_range[0], lang_range[1]):
                 ok_lang = False