ZDM Util: upgrade Go version and some of its dependencies (#70)

This PR only affects the ZDM Util.

The changes include an upgrade of the Go version from 1.16 to 1.21.7,
and upgrading several dependencies that were outdated. In particular,
the runc transitive dependency has been upgraded from 1.1.4 to 1.1.12 to
address a security vulnerability.

Additionally, there is a fix for a small compilation error in a test
which had gone unnoticed since the changes to make the ZDM Util
OS-agnostic.

The automated tests are passing and a manual smoke test was also
successful.

zdm-util/go.mod

@@ -1,20 +1,38 @@
 module zdm-proxy-automation/zdm-util
 
-go 1.16
+go 1.21
 
 require (
-	github.com/containerd/containerd v1.6.8 // indirect
-	github.com/containerd/continuity v0.3.0 // indirect
-	github.com/docker/distribution v2.8.1+incompatible // indirect
-	github.com/docker/docker v20.10.17+incompatible
-	github.com/moby/sys/mount v0.3.3 // indirect
-	github.com/moby/term v0.0.0-20220808134915-39b0c02b01ae // indirect
-	github.com/opencontainers/runc v1.1.4 // indirect
-	github.com/phayes/permbits v0.0.0-20190612203442-39d7c581d2ee // indirect
+	github.com/docker/docker v23.0.3+incompatible
+	github.com/phayes/permbits v0.0.0-20190612203442-39d7c581d2ee
 	github.com/pkg/errors v0.9.1
-	github.com/sirupsen/logrus v1.9.0 // indirect
-	github.com/stretchr/testify v1.8.0
-	golang.org/x/sys v0.0.0-20220829200755-d48e67d00261 // indirect
-	golang.org/x/time v0.0.0-20220722155302-e5dcc9cfc0b9 // indirect
-	gotest.tools/v3 v3.3.0 // indirect
+	github.com/stretchr/testify v1.8.4
+)
+
+require (
+	github.com/Azure/go-ansiterm v0.0.0-20230124172434-306776ec8161 // indirect
+	github.com/Microsoft/go-winio v0.6.1 // indirect
+	github.com/containerd/containerd v1.7.13 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/distribution/reference v0.5.0 // indirect
+	github.com/docker/distribution v2.8.3+incompatible // indirect
+	github.com/docker/go-connections v0.5.0 // indirect
+	github.com/docker/go-units v0.5.0 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/google/go-cmp v0.6.0 // indirect
+	github.com/klauspost/compress v1.17.7 // indirect
+	github.com/moby/patternmatcher v0.6.0 // indirect
+	github.com/moby/sys/sequential v0.5.0 // indirect
+	github.com/moby/term v0.5.0 // indirect
+	github.com/morikuni/aec v1.0.0 // indirect
+	github.com/opencontainers/go-digest v1.0.0 // indirect
+	github.com/opencontainers/image-spec v1.1.0 // indirect
+	github.com/opencontainers/runc v1.1.12 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/sirupsen/logrus v1.9.3 // indirect
+	golang.org/x/mod v0.15.0 // indirect
+	golang.org/x/sys v0.17.0 // indirect
+	golang.org/x/tools v0.18.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+	gotest.tools/v3 v3.5.1 // indirect
 )