Fix hreflang validation for links and assets

[yharby]

What changed

• Replace two $refs keys with $ref.
• Add tests for invalid hreflang values on links and assets.
• Update all examples to STAC 1.1.0.
• Add the fix to the changelog.

Commit split

• 59d05d5 changes only json-schema/schema.json. It is ready to cherry-pick into v1.0.0.
• 284ed6d adds the tests, STAC 1.1.0 examples, package change, and changelog entry.

Why

JSON Schema ignores the unknown $refs keyword.

An invalid hreflang value could pass validation on a link or asset.

Fixes #3.

Verification

The command used the six examples in examples/. It fetched the official STAC 1.1.0 schemas.

$ npm test
Files: 6
Valid: 6
Invalid: 0
Malformed: 0
Invalid hreflang values are rejected on links and assets.

[m-mohr]

Thanks, I'd like to cherry-pick the JSON Schema changes into 1.0.0 so that we can fix the schema without requiring a new release. And then merge the rest in.

[yharby]

Thanks, Can you check now ?

[m-mohr]

Thanks, cherry-picked the schema into 1.0.0 release so that we don't need to rerelease just for that. Otherwise, merged everything else in for the next release.