items usage is asdf-1.1.0 history_entry fails to validate items beyond the first

[braingram]

asdf-standard/resources/schemas/stsci.edu/asdf/core/asdf-1.1.0.yaml

Lines 43 to 50 in c367d14

	extensions:
	type: array
	items:
	- $ref: "extension_metadata-1.0.0"
	entries:
	type: array
	items:
	- $ref: "history_entry-1.0.0"

Since the items value is a list (instead of an object) and there is no additionalItems the draft 4 defines this behavior:
https://json-schema.org/draft-04/draft-fge-json-schema-validation-00#rfc.section.8.2.3.2
as validating only the first item in the list against the schema (since there's only 1 schema in the list).

A similar issue exists with the "backwards compatible" part of the same schema:

asdf-standard/resources/schemas/stsci.edu/asdf/core/asdf-1.1.0.yaml

Lines 24 to 27 in c367d14

	# This is to support backwards compatibility with older history formats
	- type: array
	items:
	- $ref: "history_entry-1.0.0"

Loading an ASDF file (hand edited) that includes:

history:
  extensions:
  - !core/extension_metadata-1.0.0
    extension_class: asdf.extension._manifest.ManifestExtension
    extension_uri: asdf://asdf-format.org/core/extensions/core-1.5.0
    manifest_software: !core/software-1.0.0 {name: asdf_standard, version: 1.0.4.dev187+g1458b25}
    software: !core/software-1.0.0 {name: asdf, version: 3.0.2.dev112+g143eb2d9}
  - some random stuff
  - 1

passes validation when the file is opened (but does fail when asdf attempts to check these history entries with a AttributeError: 'str' object has no attribute 'extension_uri').