Incorrect media-type for `/search` self link

[vincentsarago]

When creating the /search - GET|POST response we don't infer links, while we do it for `/items

stac-fastapi-pgstac/stac_fastapi/pgstac/core.py

Lines 523 to 532 in 4a34c90

	item_collection = await self._search_base(search_request, request=request)
	# If we have the `fields` extension enabled
	# we need to avoid Pydantic validation because the
	# Items might not be a valid STAC Item objects
	if fields := getattr(search_request, "fields", None):
	if fields.include or fields.exclude:
	return JSONResponse(item_collection) # type: ignore
	return ItemCollection(**item_collection)

stac-fastapi-pgstac/stac_fastapi/pgstac/core.py

Lines 405 to 408 in 4a34c90

	links = await ItemCollectionLinks(
	collection_id=collection_id, request=request
	).get_links(extra_links=item_collection["links"])
	item_collection["links"] = links

It will result in a self link with type="application/json", defined in

stac-fastapi-pgstac/stac_fastapi/pgstac/models/links.py

Lines 64 to 70 in 4a34c90

	def link_self(self) -> Dict:
	"""Return the self link."""
	return {
	"rel": Relations.self.value,
	"type": MimeTypes.json.value,
	"href": self.url,
	}

curl http://127.0.0.1:8000/search | jq '.links[]'

...

{
  "rel": "self",
  "type": "application/json",
  "href": "http://127.0.0.1:8000/search"
}