fix: enabled validation for all characters in CharacterConfig

src/main/java/uulm/teamname/marvelous/gamelibrary/config/CharacterConfig.java

@@ -1,6 +1,7 @@
 package uulm.teamname.marvelous.gamelibrary.config;
 
 import com.fasterxml.jackson.annotation.JsonIgnore;
+import jakarta.validation.Valid;
 import jakarta.validation.constraints.NotEmpty;
 
 import java.util.*;
@@ -11,6 +12,7 @@ import java.util.*;
 public class CharacterConfig {
 
     @NotEmpty
+    @Valid
     public CharacterProperties[] characters;
 
     @JsonIgnore private Map<String, CharacterProperties> propertyMap;