Delete humility update

This update implementation is incomplete and hasn't been touched in
a while. Delete it.

Author: labbott

Cargo.lock

@@ -94,7 +94,6 @@ members = [
     "cmd/stmsecure",
     "cmd/tasks",
     "cmd/test",
-    "cmd/update",
     "cmd/validate",
     "cmd/vpd",
     "cmd/writeword",
@@ -200,7 +199,6 @@ cmd-stackmargin = { path = "./cmd/stackmargin", package = "humility-cmd-stackmar
 cmd-stmsecure = { path = "./cmd/stmsecure", package = "humility-cmd-stmsecure" }
 cmd-tasks = { path = "./cmd/tasks", package = "humility-cmd-tasks" }
 cmd-test = { path = "./cmd/test", package = "humility-cmd-test" }
-cmd-update = { path = "./cmd/update", package = "humility-cmd-update" }
 cmd-validate = { path = "./cmd/validate", package = "humility-cmd-validate" }
 cmd-vpd = { path = "./cmd/vpd", package = "humility-cmd-vpd" }
 cmd-writeword = { path = "./cmd/writeword", package = "humility-cmd-writeword" }
@@ -348,7 +346,6 @@ cmd-stackmargin = { workspace = true }
 cmd-stmsecure = { workspace = true }
 cmd-tasks = { workspace = true }
 cmd-test = { workspace = true }
-cmd-update = { workspace = true }
 cmd-validate = { workspace = true }
 cmd-vpd = { workspace = true }
 cmd-writeword = { workspace = true }