A signature can't be generated with a url with a query param with no value

[mikaylathompson]

We're using requests-auth-aws-sigv4 to sign requests for an Opensearch cluster. One common syntax for the api is to add ?v to the end of a url to get a verbose response. This seems to break when sigv4 signing the request.

INFO:console_link.models.cluster:Performing request: GET https://cluster-endpoint.com:443/_cat/indices/_all?v
DEBUG:requests_auth_aws_sigv4:Starting authentication with amzdate=20240924T032547Z
DEBUG:requests_auth_aws_sigv4:Request URL: ParseResult(scheme='https', netloc='cluster-endpoint.com:443', path='/_cat/indices/_all', params='', query='v', fragment='')
Traceback (most recent call last):
...
  File "/root/lib/console_link/console_link/middleware/clusters.py", line 27, in cat_indices
    r = cluster.call_api(cat_indices_path)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/lib/console_link/console_link/models/cluster.py", line 155, in call_api
    r = session.request(
        ^^^^^^^^^^^^^^^^
  File "/.venv/lib64/python3.11/site-packages/requests/sessions.py", line 575, in request
    prep = self.prepare_request(req)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/.venv/lib64/python3.11/site-packages/requests/sessions.py", line 484, in prepare_request
    p.prepare(
  File "/.venv/lib64/python3.11/site-packages/requests/models.py", line 371, in prepare
    self.prepare_auth(auth, url)
  File "/.venv/lib64/python3.11/site-packages/requests/models.py", line 602, in prepare_auth
    r = auth(self)
        ^^^^^^^^^^
  File "/.venv/lib64/python3.11/site-packages/requests_auth_aws_sigv4/__init__.py", line 114, in __call__
    qs = dict(map(lambda i: i.split('='), p.query.split('&')))
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ValueError: dictionary update sequence element #0 has length 1; 2 is required

The signature succeeds if the query parameter is formatted with a value, e.g. https://cluster-endpoint.com:443/_cat/indices/_all?v=true