Allow inserting the same share multiple times

This may happen in the Gnosis implementation in case a user reuses an
identity.

Author: jannikluhn

rolling-shutter/keyper/database/keyper.sqlc.gen.go

@@ -16,7 +16,8 @@ SELECT EXISTS (
 
 -- name: InsertDecryptionKeyShare :exec
 INSERT INTO decryption_key_share (eon, epoch_id, keyper_index, decryption_key_share)
-VALUES ($1, $2, $3, $4);
+VALUES ($1, $2, $3, $4)
+ON CONFLICT DO NOTHING;
 
 -- name: SelectDecryptionKeyShares :many
 SELECT * FROM decryption_key_share