fix grammar issue with export duration message

Author: timhendriks93

addon/ops/arduino_export.py

@@ -82,5 +82,5 @@ def format_scene_name(cls):
 
         if scene_name[0].isdigit():
             scene_name = '_' + scene_name
-        
+
         return scene_name

addon/ops/base_export.py

@@ -48,8 +48,9 @@ def execute(self, context):
 
         end = time.time()
         duration = round(end - start)
+        unit = "second" if duration == 1 else "seconds"
         self.report(
-            {'INFO'}, f"Animation servo positions exported after {duration} seconds")
+            {'INFO'}, f"Animation servo positions exported after {duration} {unit}")
 
         return {'FINISHED'}