Treat security scheme as case insensitive (#2706)

Author: hornworm61

schemas/v3.0/schema.yaml

@@ -806,15 +806,17 @@ definitions:
       - description: Bearer
         properties:
           scheme:
-            enum: [bearer]
+            type: string
+            pattern: ^[Bb][Ee][Aa][Rr][Ee][Rr]$
 
       - description: Non Bearer
         not:
           required: [bearerFormat]
         properties:
           scheme:
             not:
-              enum: [bearer]
+              type: string
+              pattern: ^[Bb][Ee][Aa][Rr][Ee][Rr]$
 
   OAuth2SecurityScheme:
     type: object

schemas/v3.1/schema.yaml

@@ -767,16 +767,15 @@ $defs:
             type:
               const: http
             scheme:
-              const: bearer
+              type: string
+              pattern: ^[Bb][Ee][Aa][Rr][Ee][Rr]$
           required:
             - type
             - scheme
         then:
           properties:
             bearerFormat:
               type: string
-          required:
-            - scheme
 
       type-oauth2:
         if: