[Bug]: Add to Calendar button does not respond to Spacebar/Enter with Screen Reader on

[mvita11y]

What happened?

When keyboard focus is placed on the button with a screen reader on, the button does not respond to spacebar/enter.

How to reproduce?

Steps to reproduce:

1. NVDA/Firefox/Chrome- TAB to place focus on button with NVDA on. Press spacebar/enter
2. iOS/VoiceOver/Safari/Chrome- Swipe until focus is placed on button. Double tab to activate button

Screenshots & more

No response

System & Environment

https://add-to-calendar-button.com/
NVDA/Firefox/Chrome
iOS/VoiceOver/Safari/Chrome