Mark Some Image Attributes as Nullable (#926)

* Mark eol and vendor attributes of Image as nullable

* Add description saying expiry is null for private images

Author: zliang-akamai

openapi.yaml

@@ -23090,21 +23090,23 @@ components:
           format: date-time
           nullable: true
           description: >
-            Only Images created automatically from a deleted Linode (type=automatic) will expire.
+            Only Images created automatically from a deleted Linode (type=automatic) will expire. `null` for private Images.
           example: null
           readOnly: true
         eol:
           type: string
           format: date-time
+          nullable: true
           description: >
-            The date of the public Image's planned end of life. `None` for private Images.
+            The date of the public Image's planned end of life. `null` for private Images.
           example: '2026-07-01T04:00:00'
           readOnly: true
         vendor:
           x-linode-filterable: true
           type: string
+          nullable: true
           description: >
-            The upstream distribution vendor. `None` for private Images.
+            The upstream distribution vendor. `null` for private Images.
           example: Debian
           readOnly: true
           x-linode-cli-display: 3