"ld: library not found for -lrt" when trying to build the basic example for Swift

[cnpcshangbo]

Steps to reproduce:

(base) ➜  basics (main) swift build                                           ✱
[1/1] Planning buildCompiling plugin GenerateManual...
Building for debugging...
Build complete! (24.49s)
(base) ➜  basics (main) swift test                                            ✱
Compiling plugin GenerateManual...
Building for debugging...
ld: library not found for -lrt
[0/1] Linking s3-basicsPackageTests
error: fatalError
(base) ➜  basics (main) pwd                                                   ✱
/Users/boshang/code/aws-doc-sdk-examples/swift/example_code/s3/basics