Remove one useless env variable

data/borgmatic.d/config.yaml

@@ -1,7 +1,7 @@
 source_directories:
   - /mnt/source/
 repositories:
-  - path: ssh://${STORAGE_BOX_USER}@${STORAGE_BOX_MAIN_USER}.your-storagebox.de:23/${STORAGE_BOX_REPO_PATH}
+  - path: ssh://${STORAGE_BOX_USER}@${STORAGE_BOX_MAIN_USER}.your-storagebox.de:23/./borg-repo
 
 one_file_system: true
 remote_path: borg-1.4