Hi, 
It's been a while since I have used propellor and getting back to it feels good!
I am encountering an issue though, when I set a GH remote in my local repository: Running propellor gives me the following message

```
Up to date
Propellor build ... done
[main 40dbfa8] propellor spin
Git commit ... done
Enumerating objects: 1, done.
Counting objects: 100% (1/1), done.
Writing objects: 100% (1/1), 715 bytes | 715.00 KiB/s, done.
Total 1 (delta 0), reused 0 (delta 0), pack-reused 0
To github.com:abailly-iohk/propellor.git
   18ae6b9..40dbfa8  main -> main
Push to central git repository ... done
gpg: encrypted with 3072-bit RSA key, ID EB759F128BD1217C, created 2022-03-07
      "Arnaud Bailly <arnaud.bailly@iohk.io>"
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
Pull from central git repository ... failed
Sending privdata (280 bytes) to cardano.hydra.bzh ... done
Sending git update to cardano.hydra.bzh ... done
remote: Enumerating objects: 5, done.
remote: Counting objects: 100% (5/5), done.
remote: Compressing objects: 100% (4/4), done.
remote: Total 4 (delta 1), reused 0 (delta 0), pack-reused 0
From .
 * branch            HEAD       -> FETCH_HEAD
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
Pull from central git repository ... failed
Up to date
Propellor build ... done
```

What am I doing wrong?
