Update GitHub actions to use Node 20

.github/workflows/node.js.yml

@@ -16,7 +16,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [12.x, 14.x, 16.x]
+        node-version: [16.x, 18.x, 20.x]
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
 
     steps:

.github/workflows/npm-publish.yml

@@ -15,7 +15,7 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3
         with:
-          node-version: 16
+          node-version: 20
       - run: npm ci
       - run: npm test
 
@@ -26,7 +26,7 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3
         with:
-          node-version: 16
+          node-version: 20
           registry-url: https://registry.npmjs.org/
       - run: npm ci
       - run: npm publish --access public

README.md

@@ -217,9 +217,8 @@ Remove the `webhooks` object, if present.
 
 ### ⤓ JSON Schema related changes
 
-OAS 3.0 uses an earlier JSON Schema version (Draft 4). The tool convert `examples`
-in schemas
-to a single `example`.
+OAS 3.0 uses an earlier JSON Schema version (Draft 7). The tool converts `examples`
+in schemas to a single `example`.
 
 As a special case, if the resulting `example` includes an `id`, it is
 deleted if the `--delete-examples-with-id` CLI option is set.
@@ -321,7 +320,7 @@ be possible (`properties`, `allOf` etc.)
 
 The tool removes the `unevaluatedProperties` value, introduced in later
 versions of JSON Schema,
-as this is not supported in JSON Schema Draft 4
+as this is not supported in OAS 3.0 JSON Schema Draft 7
 used in OAS 3.0.
 
 ```yaml
@@ -447,10 +446,14 @@ format: binary
 Currently, the tool does not support the following situations.
 Contributions welcome!
 
-* `openapi-down-convert` does not convert `exclusiveMinimum` and `exclusiveMaximum`
-  as defined in JSON Schema 2012-12; these handled differently in JSON Schema Draft 4
-  used in OAS 3.0.
-* Webhooks are not addressed.
+* `openapi-down-convert` does not convert
+  `exclusiveMinimum` and
+  `exclusiveMaximum`,
+  `unevaluatedProperties`,
+  `patternProperties`
+  as defined in JSON Schema 2012-12; these are not supported in JSON Schema Draft 7
+  used in OAS 3.0
+* Webhooks are not removed. Contributions welcome!
 * The tool only supports self-contained documents. It does not follow or resolve
   external `$ref` documents embedded in the source document.
 * Request body and response body `content` object transformations, such as