add: `last modified` http header query

```
binaryedge
web.headers.last_modified:"Sun, 27 Aug 2023 16:25:16 GMT"

hunter.how
header="Sun, 27 Aug 2023 16:25:16 GMT"

netlas
http.headers.last_modified:"Sun, 27 Aug 2023 16:25:16 GMT"

censys
services.http.response.headers.Last_Modified: "Sun, 27 Aug 2023 16:25:16 GMT"
```