added support for different types in ResponseSchema class (#5789)

I added support for specifing different types with ResponseSchema
objects:

## before
`
extracted_info = ResponseSchema(name="extracted_info", description="List
of extracted information")
`
generate the following doc: ```json\n{\n\t\"extracted_info\": string //
List of extracted information}```
This brings GPT to create a JSON with only one string in the specified
field even if you requested a List in the description.

## now
`extracted_info = ResponseSchema(name="extracted_info",
type="List[string]", description="List of extracted information")
`
generate the following doc: ```json\n{\n\t\"extracted_info\":
List[string] // List of extracted information}```
This way the model responds better to the prompt generating an array of
strings.

Tag maintainers/contributors who might be interested:
  Agents / Tools / Toolkits
  @vowelparrot

Don't know who can be interested, I suppose this is a tool, so I tagged
you vowelparrot,
anyway, it's a minor change, and shouldn't impact any other part of the
framework.

langchain/output_parsers/structured.py

@@ -14,11 +14,12 @@ line_template = '\t"{name}": {type}  // {description}'
 class ResponseSchema(BaseModel):
     name: str
     description: str
+    type: str = "string"
 
 
 def _get_sub_string(schema: ResponseSchema) -> str:
     return line_template.format(
-        name=schema.name, description=schema.description, type="string"
+        name=schema.name, description=schema.description, type=schema.type
     )