Docs: use float in bpy.app.timer examples

Makes it clear seconds are not integers,
also avoids conversion to float.

doc/python_api/examples/bpy.app.timers.2.py

@@ -6,6 +6,6 @@ import bpy
 
 def every_2_seconds():
     print("Hello World")
-    return 2
+    return 2.0
 
 bpy.app.timers.register(every_2_seconds)

doc/python_api/examples/bpy.app.timers.4.py

@@ -8,5 +8,5 @@ import functools
 def print_message(message):
     print("Message:", message)
 
-bpy.app.timers.register(functools.partial(print_message, "Hello"), first_interval=2)
-bpy.app.timers.register(functools.partial(print_message, "World"), first_interval=3)
+bpy.app.timers.register(functools.partial(print_message, "Hello"), first_interval=2.0)
+bpy.app.timers.register(functools.partial(print_message, "World"), first_interval=3.0)

doc/python_api/examples/bpy.app.timers.5.py

@@ -20,6 +20,6 @@ def execute_queued_functions():
     while not execution_queue.empty():
         function = execution_queue.get()
         function()
-    return 1
+    return 1.0
 
 bpy.app.timers.register(execute_queued_functions)