fix(proto): convert map keys from string to int during deserialization (#100)

* fix(proto): convert map keys from string to int during deserialization

Fixed an issue where map keys remained as strings instead of being converted to integers during deserialization. Added proper type conversion using _value_from_dict for map keys to ensure correct integer type conversion.

* Update src/betterproto2/__init__.py

Co-authored-by: Adrien <adrien.vannson@protonmail.com>

---------

Co-authored-by: Adrien <adrien.vannson@protonmail.com>

Author: Taimast

src/betterproto2/__init__.py

@@ -66,6 +66,12 @@
 # Fields that are numerical 64-bit types
 INT_64_TYPES = [TYPE_INT64, TYPE_UINT64, TYPE_SINT64, TYPE_FIXED64, TYPE_SFIXED64]
 
+# Fields that are numerical 32-bit types
+INT_32_TYPES = [TYPE_INT32, TYPE_UINT32, TYPE_SINT32, TYPE_FIXED32, TYPE_SFIXED32]
+
+# Fields that are numerical types
+ALL_INT_TYPES = INT_64_TYPES + INT_32_TYPES
+
 # Fields that are efficiently packed when
 PACKED_TYPES = [
     TYPE_ENUM,
@@ -598,7 +604,7 @@ def _value_from_dict(value: Any, meta: FieldMetadata, field_type: type) -> Any:
             return value
         raise ValueError("Enum value must be a string or an Enum instance")
 
-    if meta.proto_type in INT_64_TYPES:  # TODO all integer types
+    if meta.proto_type in ALL_INT_TYPES:
         return int(value)
 
     if meta.proto_type == TYPE_BYTES:
@@ -1087,7 +1093,10 @@ def _from_dict_init(cls, mapping: Mapping[str, Any] | Any) -> Mapping[str, Any]:
 
                 value_cls = cls._betterproto.cls_by_field[f"{field_name}.value"]
 
-                value = {k: _value_from_dict(v, meta.map_meta[1], value_cls) for k, v in value.items()}
+                value = {
+                    _value_from_dict(k, meta.map_meta[0], type(None)): _value_from_dict(v, meta.map_meta[1], value_cls)
+                    for k, v in value.items()
+                }
 
             elif meta.repeated:
                 value = [_value_from_dict(item, meta, field_cls) for item in value]