Change save and load encode to utf-8 (#1836)

After adapting files to Portuguese and saving.
When recovering, exceptions like these are common due to Portuguese
symbols.
Fixing by changing to utf-8 standard

save
(c:\Users\jmess\miniconda3\envs\rag\Lib\site-packages\ragas\prompt\pydantic_prompt.py:333)
save_prompts
(c:\Users\jmess\miniconda3\envs\rag\Lib\site-packages\ragas\prompt\mixin.py:97)
<module> (d:\GitHub\rag_eval\Untitled-1.py:82)
_run_code (c:\Users\jmess\miniconda3\envs\rag\Lib\runpy.py:88)
_run_module_as_main (Current frame)
(c:\Users\jmess\miniconda3\envs\rag\Lib\runpy.py:198)
[Chained Exc: 'charmap' codec can't decode byte 0x81 in position 470:
character maps to <undefined>] <module>
(d:\GitHub\rag_eval\Untitled-1.py:77)
[Chained Exc: 'charmap' codec can't decode byte 0x81 in position 470:
character maps to <undefined>] load_prompts
(c:\Users\jmess\miniconda3\envs\rag\Lib\site-packages\ragas\prompt\mixin.py:119)
[Chained Exc: 'charmap' codec can't decode byte 0x81 in position 470:
character maps to <undefined>] load
(c:\Users\jmess\miniconda3\envs\rag\Lib\site-packages\ragas\prompt\pydantic_prompt.py:341)
[Chained Exc: 'charmap' codec can't decode byte 0x81 in position 470:
character maps to <undefined>] load
(c:\Users\jmess\miniconda3\envs\rag\Lib\json\__init__.py:293)
[Chained Exc: 'charmap' codec can't decode byte 0x81 in position 470:
character maps to <undefined>] decode
(c:\Users\jmess\miniconda3\envs\rag\Lib\encodings\cp1252.py:23)

Author: joaorura

src/ragas/prompt/pydantic_prompt.py

@@ -328,13 +328,13 @@ def save(self, file_path: str):
         }
         if os.path.exists(file_path):
             raise FileExistsError(f"The file '{file_path}' already exists.")
-        with open(file_path, "w") as f:
+        with open(file_path, "w", encoding="utf-8") as f:
             json.dump(data, f, indent=2, ensure_ascii=False)
             print(f"Prompt saved to {file_path}")
 
     @classmethod
     def load(cls, file_path: str) -> "PydanticPrompt[InputModel, OutputModel]":
-        with open(file_path, "r") as f:
+        with open(file_path, "r", encoding="utf-8") as f:
             data = json.load(f)
 
         # You might want to add version compatibility checks here