feat: migrate openapi definitions to 3.1 (#1)

Author: ParanoidUser

openapi/components/schemas/AuthoredChallenge.yaml

@@ -16,13 +16,11 @@ properties:
     type: string
     description: Description of the kata in Markdown.
   rank:
-    type: integer
+    type: [ integer, "null" ]
     description: Rank of the kata if approved.
-    nullable: true
   rankName:
-    type: string
+    type: [ string, "null" ]
     description: Rank name of the kata if approved.
-    nullable: true
   tags:
     type: array
     description: Array of tags associated with the kata.

openapi/components/schemas/CodeChallenge.yaml

@@ -53,16 +53,14 @@ properties:
     type: string
     description: Date and time when the kata was created.
   publishedAt:
-    type: string
-    nullable: true
+    type: [ string, "null" ]
     description: Date and time when the kata was first published.
   approvedBy:
     # nullable: true
     # description: The approver of the kata.
     $ref: ./CodeChallengeContributor.yaml
   approvedAt:
-    type: string
-    nullable: true
+    type: [ string, "null" ]
     description: Date and time when the kata was approved.
   totalCompleted:
     type: integer

openapi/components/schemas/CodeChallengeRank.yaml

@@ -2,16 +2,13 @@ type: object
 description: Object describing the rank of the kata if approved.
 properties:
   id:
-    type: integer
-    nullable: true
+    type: [ integer, "null" ]
     description: Rank in integer. [-8, -1] maps to kyu, [1, 8] maps to dan.
   name:
-    type: string
-    nullable: true
+    type: [ string, "null" ]
     description: Either {-rank} kyu or {rank} dan.
   color:
-    type: string
-    nullable: true
+    type: [ string, "null" ]
     description: |
       The color of the rank. Possible colors are white (7-8 kyu), yellow (5-6 kyu), 
       blue (3-4 kyu), purple (1-2 kyu), black (1-4 dan), and red (5-8 dan).

openapi/components/schemas/User.yaml

@@ -13,23 +13,19 @@ properties:
     type: string
     description: Username of the user.
   name:
-    type: string
-    nullable: true
+    type: [ string, "null" ]
     description: Name of the user.
   honor:
     type: integer
     description: Total honor points earned by the user.
   clan:
-    type: string
-    nullable: true
+    type: [ string, "null" ]
     description: Name of the clan.
   leaderboardPosition:
-    type: integer
-    nullable: true
+    type: [ integer, "null" ]
     description: The user's position on the overall leaderboard.
   skills:
-    type: array
-    nullable: true
+    type: [ array, "null" ]
     description: Array of skills entered by the user.
     items:
       type: string

openapi/openapi.yaml

@@ -1,4 +1,4 @@
-openapi: 3.0.3
+openapi: 3.1.0
 info:
   version: 0.2.0
   title: Codewars API