fix bad in/notin filter in search offers

[vastzuby]

Steps to Reproduce

Navigate to the API docs page for Search Offers: search offers - Vast.ai Documentation – Affordable GPU Cloud Marketplace

Click the “Try It” button to open the interactive interface.

Add an “in” or “notin” property to one of the objects (“geolocation” is a good one to try)

Attempt to add a list as an argument. Eg., [“NL”, “CA”]

Expected Result

The list should be added to the request appropriately. Eg.,
"geolocation": { "in": [ "US", "NL" ] }

Actual Result

The list[] can only be added as a string. The whole list is wrapped in quotes, and any quotes you passed will be escaped. Eg.,

"geolocation": { "in": "[ "US", "NL" ]" }

This results in a 400 error when the request is submitted.

{
"error": "invalid_request",
"msg": " ask_contract_offers.geolocode in 128201953: query values can't be None"
}