feat: added convertTimezon & isValidTimezone

Author: codebyaadi

src/index.ts

@@ -8,3 +8,4 @@ export { getFileExtension } from '@/utils/get-file-extension'
 export { formatFileSize } from '@/utils/format-file-size'
 export { getBase64 } from '@/utils/get-base64'
 export { timeDelta } from '@/utils/timedelta'
+export { convertTimezone, isValidTimezone } from '@/utils/tstz'