feat: ianaTimezoneSchema to support UTC string

Author: kirillgroshkov

src/validation/joi/joi.shared.schemas.test.ts

@@ -169,6 +169,7 @@ test('ianaTimezoneSchema', () => {
   const schema = ianaTimezoneSchema
 
   validate('Europe/London', schema)
+  validate('UTC', schema) // to support unit testing
   expect(() => validate(undefined, schema)).toThrowErrorMatchingInlineSnapshot(
     `""value" is required"`,
   )

src/validation/joi/joi.shared.schemas.ts

@@ -157,7 +157,8 @@ export const utcOffsetSchema = numberSchema
   .dividable(15)
 
 export const ianaTimezoneSchema = stringSchema
-  .valid(...Intl.supportedValuesOf('timeZone'))
+  // UTC is added to assist unit-testing, which uses UTC by default (not technically a valid Iana timezone identifier)
+  .valid(...Intl.supportedValuesOf('timeZone'), 'UTC')
   .messages({
     'any.only': `must be a valid IANA timezone string`,
   })