Generate data through specific date instead of through file name

In upstream data, the New Year's Day holiday is included in the file for
the next year. For example, '2022-12-31' would be in 2023.json. This
will result in incorrect data being generated through the file name.

Fixed: #1

src/holiday.ts

@@ -49,11 +49,13 @@ export class Holiday {
   }
 
   private parseYearJson(holiday_cn_json_schema: HolidayCnJsonSchema) {
-    const year: number = holiday_cn_json_schema.year
+    holiday_cn_json_schema.days.forEach((holiday_json: HolidayJson) => {
+      const year = new Date(holiday_json.date).getFullYear()
 
-    this.data[year] = new Map()
+      if (this.data[year] === undefined) {
+        this.data[year] = new Map()
+      }
 
-    holiday_cn_json_schema.days.forEach((holiday_json: HolidayJson) => {
       this.data[year][holiday_json.date] = {
         name: holiday_json.name,
         type: holiday_json.isOffDay ? 'publicHoliday' : 'publicWorkday',

test/holiday.test.ts

@@ -37,4 +37,8 @@ describe('class', () => {
     expect(holiday.isPublicHoliday(new Date('2023-10-1'))).toBe(true)
     expect(holiday.publicHolidayName(new Date('2023-10-1'))).toBe('中秋节、国庆节')
   })
+
+  it('2023-12-31 is public holiday', () => {
+    expect(holiday.isPublicHoliday(new Date('2022-12-31'))).toBe(true)
+  })
 })