from_dict() does not cast floating point types

When you pass in the dictionary a float to an int field, this is casted to int (line 890 `betterproto/__init__.py`). I would expect a similar behaviour in the reverse situation when you pass an int to a float field. Right now you end up with an object having an int in a field which should contain a float.

Start in betterproto/__init__.py at line 890 and trace from_dict() handling for integer and floating-point fields. Confirm the expected reverse conversion, then verify that integer inputs produce float-valued fields without changing the existing integer conversion behavior.

Written by the indexing model from the issue text.