Add support to update key value

[GuillaumeFalourd]

What is happening

The action currently doesn't update a key value, and will create a new line into the file (duplicating the key) instead of updating the key value.

What is expected

Add the implementation to update the value in case the key is already present inside the file.

[github-actions]

Thank you for opening this ISSUE. We'll give you a return ASAP 👍