Update Swift packages (#568)
Update Swift packages (#568)

Motivation:

One of interop test cases may hang prior to NIO 2.7.1 causing the CI to
fail.

Modifications:

Update Package.resolved so that NIO 2.7.1, which contains a fix for the
aforementioned bug, is used.

Result:

Interop tests are less likely to hang.
grpc/grpc-swift,grpc/grpc-swift,grpc/grpc-swift,grpc/grpc-swift,grpc/grpc-swift