fix(tests): Call pylint binary instead of the module

pylint is a command-line tool, and it should not be invoked as a
module, aka `pythonX.Y -m pylint`.

Bug-Debian: https://bugs.debian.org/1028704

tests/test_pylint.py

@@ -37,9 +37,9 @@ class PylintTestCase(unittest.TestCase):
     def test_pylint(self):
         """Test: Run pylint on Python source code."""
 
-        cmd = [sys.executable, "-m", "pylint", "--rcfile=" + CONFIG, "--"] + get_source_files()
+        cmd = ["pylint", "--rcfile=" + CONFIG, "--"] + get_source_files()
         if os.environ.get("SKIP_LINTERS"):
-            cmd.insert(4, "--errors-only")
+            cmd.insert(2, "--errors-only")
         if unittest_verbosity() >= 2:
             sys.stderr.write(f"Running following command:\n{' '.join(cmd)}\n")
         with subprocess.Popen(