service/tests: Fix psutil deprecation warning

[bkeryan]

• This contribution adheres to CONTRIBUTING.md.

What does this Pull Request accomplish?

Update test_security.py to call Process.net_connections() instead of Process.connections().

Update min version of psutil.

Why should this Pull Request be merged?

Fix this deprecation warning:

tests/acceptance/test_security.py::test___loopback_measurement___listening_on_loopback_interface
  D:\dev\measurement-plugin-python\packages\service\tests\acceptance\test_security.py:19: DeprecationWarning: connections() is deprecated and will be removed; use net_connections() instead
    for conn in psutil.Process().connections()

What testing has been done?

Ran updated test.

[github-actions]

Test Results

    30 files  ±0      30 suites  ±0   40m 51s ⏱️ - 1m 56s
   632 tests ±0     632 ✅ ±0      0 💤 ±0  0 ❌ ±0 
15 580 runs  ±0  14 510 ✅ ±0  1 070 💤 ±0  0 ❌ ±0 

Results for commit 975a221. ± Comparison against base commit 7a3f848.

♻️ This comment has been updated with latest results.