Remove external mock dependency

Since the minimum version of Python we support contains mock in the
standard library, we should switch to it and remove one external
dependency.

requirements-dev.txt

@@ -7,7 +7,6 @@ pytest-cov==5.0.0
 pytest-json-report==1.5.0
 pyflakes==3.2.0
 pylama==8.4.1
-mock==5.1.0
 mypy==1.10.0
 types-PyYAML==6.0.12.20240311
 types-requests==2.32.0.20240521

test/eos/test_heredoc.py

@@ -1,4 +1,4 @@
-import mock
+from unittest import mock
 import pytest
 from textwrap import dedent
 

test/nxos/test_getters.py

@@ -1,12 +1,12 @@
 """Tests for getters."""
 
+from unittest.mock import patch
+
 from napalm.base.test.getters import BaseTestGetters, wrap_test_cases
 from napalm.base.test import helpers
 from napalm.base import models
 
 import pytest
-from mock import patch
-
 
 def mock_time():
     return 1500000000.000000

test/nxos_ssh/test_getters.py

@@ -1,12 +1,12 @@
 """Tests for getters."""
 
+from unittest.mock import patch
+
 from napalm.base.test.getters import BaseTestGetters, wrap_test_cases
 from napalm.base.test import helpers
 from napalm.base import models
 
 import pytest
-from mock import patch
-
 
 def mock_time():
     return 1500000000.000000