fix(curriculum): remove isRequired from chinese

curriculum/challenges/chinese/06-quality-assurance/quality-assurance-projects/american-british-translator.chinese.md

@@ -3,7 +3,6 @@ id: 5e601c0d5ac9d0ecd8b94afe
 title: American British Translator
 challengeType: 4
 isHidden: false
-isRequired: true
 ---
 
 ## Description

curriculum/challenges/chinese/06-quality-assurance/quality-assurance-projects/issue-tracker.chinese.md

@@ -2,7 +2,6 @@
 id: 587d8249367417b2b2512c42
 title: Issue Tracker
 challengeType: 4
-isRequired: true
 videoUrl: ''
 localeTitle: 问题跟踪器
 ---

curriculum/challenges/chinese/06-quality-assurance/quality-assurance-projects/metric-imperial-converter.chinese.md

@@ -2,7 +2,6 @@
 id: 587d8249367417b2b2512c41
 title: Metric-Imperial Converter
 challengeType: 4
-isRequired: true
 videoUrl: ''
 localeTitle: 公制 - 英制转换器
 ---

curriculum/challenges/chinese/06-quality-assurance/quality-assurance-projects/personal-library.chinese.md

@@ -2,7 +2,6 @@
 id: 587d824a367417b2b2512c43
 title: Personal Library
 challengeType: 4
-isRequired: true
 videoUrl: ''
 localeTitle: 个人图书馆
 ---

curriculum/challenges/chinese/06-quality-assurance/quality-assurance-projects/sudoku-solver.chinese.md

@@ -3,7 +3,6 @@ id: 5e601bf95ac9d0ecd8b94afd
 title: Sudoku Solver
 challengeType: 4
 isHidden: false
-isRequired: true
 ---
 
 ## Description