cloud-nuke 0.50.0 አውርድ

Fixes
- IPAM custom-allocation: scope state per instance. The pool/CIDR metadata captured at list time lived in a package-level global and was reset by every region's InitClient, wiping data needed at deletion time. Multi-region runs hit unable to find pool allocation info for ipam-pool-alloc-.... Regression from #992. State is now closure-scoped per resource instance, so each region's metadata is isolated. (#1130)
- ECS cluster: deregister container instances before delete. EC2-launch-type clusters with registered instances failed with ClusterContainsContainerInstancesException. The nuker now lists container instances and force-deregisters them as a step before DeleteCluster. (#1131)
- Network interface: classify 'currently in use' as a warning. InvalidParameterValue: Network interface 'eni-...' is currently in use is treated like the existing DependencyViolation ordering errors, non-fatal and resolved on the next run once the attaching resource is gone. (#1132)
Full Changelog: v0.49.0...v0.50.0