Run ifconfig tests in Python 3 CI

Python 3 manylinux CI image does not have net-tools (hence ifconfig)
pre-installed, so tests using it were skippied altogether.

Signed-off-by: Ben Raz <ben9923@gmail.com>

.github/workflows/build.yml

@@ -33,7 +33,8 @@ jobs:
         include:
           - {name: Linux, python: '3.9', os: ubuntu-latest}
     env:
-      CIBW_BEFORE_ALL_LINUX: command -v apk && apk --no-cache add coreutils procps || true
+      CIBW_BEFORE_ALL_LINUX: command -v apk && apk --no-cache add coreutils procps ||
+                             (yum install -y net-tools && yum clean all)
       CIBW_TEST_COMMAND:
         PYTHONWARNINGS=always PYTHONUNBUFFERED=1 PSUTIL_DEBUG=1 python {project}/psutil/tests/runner.py &&
         PYTHONWARNINGS=always PYTHONUNBUFFERED=1 PSUTIL_DEBUG=1 python {project}/psutil/tests/test_memleaks.py