Corrects the type of field validation when reviewing a photo

src/main/kotlin/net/halfbinary/scavengerhuntapi/model/request/ReviewPhotoRequest.kt

@@ -1,9 +1,9 @@
 package net.halfbinary.scavengerhuntapi.model.request
 
-import jakarta.validation.constraints.NotBlank
+import jakarta.validation.constraints.NotNull
 import net.halfbinary.scavengerhuntapi.model.PhotoStatus
 
 data class ReviewPhotoRequest(
-    @field:NotBlank(message = "Status must not be blank")
+    @field:NotNull(message = "Status must not be null")
     val status: PhotoStatus
 )