Update code to be Py3.7+ to reduce merge forward conflicts

Author: s0undt3ch

src/saltext/libvirt_events/engines/libvirt_events.py

@@ -189,7 +189,7 @@ def _get_domain_event_detail(event, detail):
     if event_name == "unknown":
         return event_name, "unknown"
 
-    prefix = "VIR_DOMAIN_EVENT_{}_".format(event_name.upper())
+    prefix = f"VIR_DOMAIN_EVENT_{event_name.upper()}_"
     detail_name = _get_libvirt_enum_string(prefix, detail)
 
     return event_name, detail_name
@@ -333,9 +333,7 @@ def get_address(addr):
         transform address structure into event data piece
         """
         return {
-            "family": _get_libvirt_enum_string(
-                "{}_ADDRESS_".format(prefix), addr["family"]
-            ),
+            "family": _get_libvirt_enum_string(f"{prefix}_ADDRESS_", addr["family"]),
             "node": addr["node"],
             "service": addr["service"],
         }
@@ -680,14 +678,14 @@ def _register_callback(cnx, tag_prefix, obj, event, real_id):
     """
     libvirt_name = real_id
     if real_id is None:
-        libvirt_name = "VIR_{}_EVENT_ID_{}".format(obj, event).upper()
+        libvirt_name = f"VIR_{obj}_EVENT_ID_{event}".upper()
 
     if not hasattr(libvirt, libvirt_name):
         log.warning('Skipping "%s/%s" events: libvirt too old', obj, event)
         return None
 
     libvirt_id = getattr(libvirt, libvirt_name)
-    callback_name = "_{}_event_{}_cb".format(obj, event)
+    callback_name = f"_{obj}_event_{event}_cb"
     callback = globals().get(callback_name, None)
     if callback is None:
         log.error("Missing function %s in engine", callback_name)