Fix: Change data type of SocialMember's id

Resolves: #4

Author: jiwon83

domain/jpa-member-domain/src/main/java/com/wypl/jpamemberdomain/member/SocialMember.java

@@ -23,7 +23,7 @@
 public class SocialMember {
     @Id
     @Column(name = "member_id")
-    private int id;
+    private Long id;
 
     @MapsId
     @OneToOne(fetch = FetchType.LAZY)