Modbus fixes to work with pymodbus 1.3.1 (#8365)

* Fixed a bug where changing fan speed was not possible

* Bump pymodbus version to 1.3.1 to fix issue #8285

* Changed all modbus components so that they use CONF_SLAVE from const.py

* Fix checking result from a modbus transaction

* Add missing decorator

* Added modbus write coil service and added descriptions

* Removed a hiding debug print

homeassistant/components/services.yaml

@@ -483,3 +483,28 @@ apple_tv:
   apple_tv_scan:
     description: Scan for Apple TV devices.
 
+modbus:
+  write_register:
+    description: Write to a modbus holding register
+    fields:
+      unit:
+        description: Address of the modbus unit
+        example: 21
+      address:
+        description: Address of the holding register to write to
+        example: 0
+      value:
+        description: Value to write
+        example: 0
+  write_coil:
+    description: Write to a modbus coil
+    fields:
+      unit:
+        description: Address of the modbus unit
+        example: 21
+      address:
+        description: Address of the register to read
+        example: 0
+      state:
+        description: State to write
+        example: false