GPG signature invalid

[fgtham]

Currently, apt update shows this error:

Err:7 https://apt.tabfugni.cc/debian stable InRelease
  The following signatures were invalid: EXPKEYSIG EC478DAB713A4BC3 thoughtbot <[email protected]>
...
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://apt.tabfugni.cc/debian stable InRelease: The following signatures were invalid: EXPKEYSIG EC478DAB713A4BC3 thoughtbot <[email protected]>
W: Failed to fetch https://apt.tabfugni.cc/debian/dists/stable/InRelease  The following signatures were invalid: EXPKEYSIG EC478DAB713A4BC3 thoughtbot <[email protected]>

My apt source:

deb [signed-by=/etc/apt/keyrings/thoughtbot.gpg] https://apt.tabfugni.cc/debian/ stable main

I downloaded the key from https://apt.tabfugni.cc/thoughtbot.gpg.key.