refactor: Rename TokenInfo to JwtToken (#3)

Author: youjin09222

server-toy-project/src/main/java/com/gdsc_teamb/servertoyproject/jwt/TokenInfo.java renamed to server-toy-project/src/main/java/com/gdsc_teamb/servertoyproject/jwt/JwtToken.java

@@ -8,7 +8,7 @@
 @Data
 @AllArgsConstructor
 // 클라이언트에 토큰을 보내기 위한 DTO
-public class TokenInfo {
+public class JwtToken {
     private String grantType;
     private String accessToken;
     private String refreshToken;