Pages function does not work for search.

`Pages` for search does not work:

```py
gh = GhApi(token=gh_token)
search = pages(gh.search.code, gh.last_page(), '"test"').concat
```

Will yield the following error:
```
File "/Users/***/venv/lib/python3.9/site-packages/ghapi/page.py", line 57, in last_page
header = self.recv_hdrs.get('Link', '')
File "/Users/***/venv/lib/python3.9/site-packages/ghapi/core.py", line 124, in __getattr__
def __getattr__(self,k): return self.groups[k] if 'groups' in vars(self) and k in self.groups else stop(AttributeError(k))
File "/Users/***/venv/lib/python3.9/site-packages/fastcore/basics.py", line 205, in stop
raise e
AttributeError: recv_hdrs
```