Require league/flysystem:^1

See backup-manager/backup-manager#186

Author: Jelle-S

composer.json

@@ -8,6 +8,7 @@
         "consolidation/robo": "^3.0",
         "phpseclib/phpseclib": "^3.0",
         "backup-manager/backup-manager": "^3",
+        "league/flysystem": "^1",
         "gordalina/cachetool": "^8",
         "digipolisgent/command-builder": "^1.2",
         "digipolisgent/robo-digipolis-general": "^2.0.0"