👷(ci) sops: configure workflows to use sops secrets

Github secrets are difficult to maintain in time because we do not have
a way to track them efficiently. So to avoid this issue, we prefer to use
sops encrypted files to manage our secrets.

.sops.yaml

@@ -0,0 +1,7 @@
+creation_rules:
+  # Here we have
+  # - jacques key-id: age15fyxdwmg5mvldtqqus87xspuws2u0cpvwheehrtvkexj4tnsqqysw6re2x
+  # - github-repo key-id: age16hnlml8yv4ynwy0seer57g8qww075crd0g7nsundz3pj4wk7m3vqftszg7
+  - age:
+      age15fyxdwmg5mvldtqqus87xspuws2u0cpvwheehrtvkexj4tnsqqysw6re2x,
+      age16hnlml8yv4ynwy0seer57g8qww075crd0g7nsundz3pj4wk7m3vqftszg7