review: increase modulus length to 500 chars (==3000 bits)

this is in accordance with the BSI requirements for 2023+

spec/schemas/jwk.yml

@@ -43,8 +43,8 @@ properties:
     maxLength: 64
   n:
     type: string
-    description: Modulus
-    minLength: 128
+    description: Modulus. The value 500 represents a key length of 3000 bits.
+    minLength: 500
   e:
     type: string
     description: Exponent