fix(curriculum): remove isRequired from chinese

curriculum/challenges/chinese/09-information-security/information-security-projects/anonymous-message-board.chinese.md

@@ -2,7 +2,6 @@
 id: 587d824a367417b2b2512c45
 title: Anonymous Message Board
 challengeType: 4
-isRequired: true
 videoUrl: ''
 localeTitle: 匿名留言板
 ---

curriculum/challenges/chinese/09-information-security/information-security-projects/port-scanner.chinese.md

@@ -3,7 +3,6 @@ id: 5e46f979ac417301a38fb932
 title: Port Scanner
 challengeType: 10
 isHidden: false
-isRequired: true
 ---
 
 ## Description

curriculum/challenges/chinese/09-information-security/information-security-projects/secure-real-time-multiplayer-game.chinese.md

@@ -3,7 +3,6 @@ id: 5e601c775ac9d0ecd8b94aff
 title: Secure Real Time Multiplayer Game
 challengeType: 4
 isHidden: false
-isRequired: true
 ---
 
 ## Description

curriculum/challenges/chinese/09-information-security/information-security-projects/sha-1-password-cracker.chinese.md

@@ -3,7 +3,6 @@ id: 5e46f983ac417301a38fb933
 title: SHA-1 Password Cracker
 challengeType: 10
 isHidden: false
-isRequired: true
 ---
 
 ## Description

curriculum/challenges/chinese/09-information-security/information-security-projects/stock-price-checker.chinese.md

@@ -2,7 +2,6 @@
 id: 587d824a367417b2b2512c44
 title: Stock Price Checker
 challengeType: 4
-isRequired: true
 videoUrl: ''
 localeTitle: 股票价格检查
 ---