Update consumed version of `ion-schema-rust` to support all core types

[jobarr-amzn]

The version of ion-schema-rust used here does not seem to support the document core type, described in the Ion schema spec here.

Given this content adapted from the document example in the Ion Schema specification docs:

❯ cat document_example.isl
$ion_schema_1_0

schema_header::{
}

type::{
  name: IonSchema,
  type: document,
  ordered_elements: [
    { type: Header, occurs: optional },
    { type: Type,   occurs: range::[0, max] },
    { type: Footer, occurs: optional },
  ],
}

type::{
  name: Header,
  type: struct,
  annotations: [required::schema_header],
  fields: {
    imports: ImportList,
  },
}

type::{
  name: ImportList,
  type: list
}

type::{
  name: Type,
  type: struct,
  annotations: [required::type],
  fields: {
    name: symbol,
  },
}

type::{
  name: Footer,
  type: struct,
  annotations: [required::schema_footer],
}

schema_footer::{
}

ion-schema-rust fails because there is no known document type:

❯ ion beta schema validate \
--input document_example.isl \
--schema document_example.isl \
--directory . \
--type IonSchema

Error: Could not resolve type reference: "document" does not exist

It looks like document support was added in this PR: https://github.com/amzn/ion-schema-rust/pull/116 .