HumioLib does not sanitize URLs in some cases

[chrisbvt]

Describe the bug
HumioLib doesn't sanitize URLs and remove the trailing slash from them in some cases. This causes for weird errors such as the one below:
HumioHTTPException: ('HTTP method not allowed, supported methods: GET', 405)

To Reproduce
Steps to reproduce the behavior:

1. Initialize the HumioLib with a url to your cluster and a '/' at the end. For example https://myhumiocluster.com/
2. Attempt to run a query with this client.

Expected behavior
I would expect a more clear answer on the URL being incorrect. Currently it gives the above error which is not accurate to the problem

Desktop (please complete the following information):

• MacOS