fix(redis_func_cache): preserve line breaks in clean_lua_script

- Replace "" with "\n" when joining non-empty lines in the Lua script
- This change ensures that the cleaned script maintains proper line breaks

Author: tanbro

src/redis_func_cache/utils.py

@@ -108,7 +108,7 @@ def filter(self, lexer, stream, options):
         lexer.add_filter(filter())  # pyright: ignore[reportCallIssue]
         code = "".join(tok_str for _, tok_str in lexer.get_tokens(source))
         # remote empty lines
-        return "".join(s for line in code.splitlines() if (s := line.strip()))
+        return "\n".join(s for line in code.splitlines() if (s := line.strip()))
 
     else:
         warn("pygments is not installed, return source code as is", ImportWarning)