chore: remove unused unittest imports (#1728)

Co-authored-by: Jordan Woods <13803242+jorwoods@users.noreply.github.com>

Author: jorwoods

test/http/test_http_requests.py

@@ -1,6 +1,5 @@
 import pytest
 import tableauserverclient as TSC
-import unittest
 import requests
 import requests_mock
 

test/test_metadata.py

@@ -1,6 +1,5 @@
 import json
 from pathlib import Path
-import unittest
 
 import pytest
 import requests_mock

test/test_server_info.py

@@ -1,5 +1,4 @@
 from pathlib import Path
-import unittest
 
 import pytest
 import requests_mock