Upgrade to Pants 2.28.0 (#24)

Author: benjyw

pants.toml

@@ -2,7 +2,7 @@
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
 [GLOBAL]
-pants_version = "2.26.0"
+pants_version = "2.28.0"
 backend_packages = ["pants.backend.experimental.go"]
 
 [anonymous-telemetry]