Fix pylint warnings in examples

The `__init__.py` files were not previously checked with `pylint`
because of sybil bug.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

src/frequenz/sdk/actor/__init__.py

@@ -77,6 +77,7 @@ class communicates through message passing. Even when no particular message pass
 ???+ example
 
     ```python
+    import asyncio
     from frequenz.sdk.actor import Actor, run
 
     class MyActor(Actor):
@@ -85,7 +86,7 @@ async def _run(self) -> None:
                 print("Hello World!")
                 await asyncio.sleep(1)
 
-    await run(MyActor()) # (1)!
+    await asyncio.run(MyActor()) # (1)!
     ```
 
     1. This line will block until the actor completes its execution or is manually stopped.
@@ -187,27 +188,27 @@ class we are implementing to make sure actors are properly initialized.
     class EchoActor(Actor):  # (1)!
         def __init__(
                 self,
-                input: Receiver[int],  # (2)!
-                output: Sender[int],  # (3)!
+                receiver: Receiver[int],  # (2)!
+                sender: Sender[int],  # (3)!
                 name: str | None = None,  # (4)!
         ) -> None:
             super().__init__(name=name) # (5)!
-            self._input: Receiver[int] = input  # (6)!
-            self._output: Sender[int] = output  # (7)!
+            self._input: Receiver[int] = receiver  # (6)!
+            self._output: Sender[int] = sender  # (7)!
     ```
 
     1. We define a new actor class called `EchoActor` that inherits from
         [`Actor`][frequenz.sdk.actor.Actor].
 
-    2. We accept an `input` argument that will be used to receive messages from
+    2. We accept an `receiver` argument that will be used to receive messages from
         a channel.
-    3. We accept an `output` argument that will be used to send messages to a channel.
+    3. We accept an `sender` argument that will be used to send messages to a channel.
     4. We accept an optional `name` argument that will be used to identify the actor in
         logs.
     5. We call [`Actor.__init__()`][frequenz.sdk.actor.Actor.__init__] to make sure the
         actor is properly initialized.
-    6. We store the `input` argument in a *private* attribute to use it later.
-    7. We store the `output` argument in a *private* attribute to use it later.
+    6. We store the `receiver` argument in a *private* attribute to use it later.
+    7. We store the `sender` argument in a *private* attribute to use it later.
 
 ### The `_run()` Method