tests: add importorskip for eaton devices

The eaton devices use pysnmp for communication, which is not a required
dependency. Add an importorskip to skip them if the module is not
available.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
(cherry picked from commit 968ab8a)

Author: Emantor

tests/test_powerdriver.py

@@ -242,7 +242,6 @@ def test_create_shelly_gen1_backend_with_url_in_host(self, target, mocker, host)
     def test_import_backends(self):
         import labgrid.driver.power
         import labgrid.driver.power.apc
-        import labgrid.driver.power.eaton
         import labgrid.driver.power.digipower
         import labgrid.driver.power.digitalloggers_http
         import labgrid.driver.power.gude
@@ -255,6 +254,10 @@ def test_import_backends(self):
         import labgrid.driver.power.eg_pms2_network
         import labgrid.driver.power.shelly_gen1
 
+    def test_import_backend_eaton(self):
+        pytest.importorskip("pysnmp")
+        import labgrid.driver.power.eaton
+
     def test_import_backend_siglent(self):
         pytest.importorskip("vxi11")
         import labgrid.driver.power.siglent