fix: issue 템플릿에서 빈 placeholder 제거

Author: leegwichan

.github/ISSUE_TEMPLATE/01-feat-template.yml

@@ -27,6 +27,5 @@ body:
     attributes:
       label: '📅 마감일'
       description: '마감일을 입력해주세요 (YY.MM.DD)'
-      placeholder: ''
     validations:
       required: false

.github/ISSUE_TEMPLATE/02-fix-template.yml

@@ -27,6 +27,5 @@ body:
     attributes:
       label: '📅 마감일'
       description: '마감일을 입력해주세요 (YY.MM.DD)'
-      placeholder: ''
     validations:
       required: false

.github/ISSUE_TEMPLATE/03-hotfix-template.yml

@@ -27,6 +27,5 @@ body:
     attributes:
       label: '📅 마감일'
       description: '마감일을 입력해주세요 (YY.MM.DD)'
-      placeholder: ''
     validations:
       required: false

.github/ISSUE_TEMPLATE/04-docs-template.yml

@@ -27,6 +27,5 @@ body:
     attributes:
       label: '📅 마감일'
       description: '마감일을 입력해주세요 (YY.MM.DD)'
-      placeholder: ''
     validations:
       required: false

.github/ISSUE_TEMPLATE/05-refactor-template.yml

@@ -27,6 +27,5 @@ body:
     attributes:
       label: '📅 마감일'
       description: '마감일을 입력해주세요 (YY.MM.DD)'
-      placeholder: ''
     validations:
       required: false

.github/ISSUE_TEMPLATE/06-test-template.yml

@@ -27,6 +27,5 @@ body:
     attributes:
       label: '📅 마감일'
       description: '마감일을 입력해주세요 (YY.MM.DD)'
-      placeholder: ''
     validations:
       required: false

.github/ISSUE_TEMPLATE/07-chore-template.yml

@@ -27,6 +27,5 @@ body:
     attributes:
       label: '📅 마감일'
       description: '마감일을 입력해주세요 (YY.MM.DD)'
-      placeholder: ''
     validations:
       required: false

.github/ISSUE_TEMPLATE/08-ci-template.yml

@@ -27,6 +27,5 @@ body:
     attributes:
       label: '📅 마감일'
       description: '마감일을 입력해주세요 (YY.MM.DD)'
-      placeholder: ''
     validations:
       required: false