Fix imports for micropython

shared/alerts.py

@@ -1,6 +1,10 @@
 import time
-import asyncio
-import inspect
+try:    
+    import asyncio
+    import inspect
+    ASYNCIO = True
+except ImportError:
+    ASYNCIO = False
 
 class AlertManager:
     def __init__(self):
@@ -12,7 +16,7 @@ class AlertManager:
 
     def call_on_alert_callback(self, alert):
         if self.on_alert_callback:
-            if inspect.iscoroutinefunction(self.on_alert_callback):
+            if ASYNCIO and inspect.iscoroutinefunction(self.on_alert_callback):
                 # Schedule coroutine on the running loop without blocking
                 try:
                     loop = asyncio.get_running_loop()