Fixed logic inside core.py for proxy error (#83)

* Fixed error where would attempt to fetch with proxy as empty string.

* Pushed change.

theHarvester/lib/core.py

@@ -435,7 +435,7 @@ async def fetch(session, url, params='', json=False, proxy="") -> Union[str, dic
                     async with session.get(url, params=params, proxy=proxy) as response:
                         return await response.text() if json is False else await response.json()
                 else:
-                    async with session.get(url, proxy=proxy) as response:
+                    async with session.get(url) as response:
                         await asyncio.sleep(2)
                         return await response.text() if json is False else await response.json()