Gracefully handle no matches

[gcrois]

Current nonmatching errors produce the following output:

------------------------------------------------
Running Input...
------------------------------------------------

avocat> running command: git clone sijbdfga
out>
err> fatal: repository 'sijbdfga' does not exist
err>
avocat> (exitcode: 128 )

------------------------------------------------
Finding Solution...
------------------------------------------------

Traceback (most recent call last):
  File "/usr/lib/python3.8/runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.8/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/mnt/e/linhome/Projects/avocat/avocat/__main__.py", line 59, in <module>
    sol = avocat.db.find_sol(out, err)
  File "/mnt/e/linhome/Projects/avocat/avocat/db/__init__.py", line 33, in find_sol
    Qs = se.find_Qs(err)[:4]
  File "/mnt/e/linhome/Projects/avocat/avocat/db/stackexchange.py", line 93, in find_Qs
    raise Exception(f"failed to get any results from request: {req_url}")
Exception: failed to get any results from request: https://api.stackexchange.com/2.3/search/advanced?order=desc&sort=votes&q=fatal%3A+repository+%27sijbdfga%27+does+not+exist%0A&site=askubuntu&answers=1&filter=withbody&key=d3qKMek1GCXs8ED6ee6ANA((```

Whenever possible, we should avoid using python's native exception handler for the outword-facing version of the UI.

Perhaps we could ask the user if they want to construct their own query?