remove API-version compatibility for API < v1.44

Support for API versions < v1.44 was removed in the client in [moby@96b29f5]
and [moby@7652f38], so we can remove fallback-code from the CLI as well,
as it won't be able to use those versions.

[moby@96b29f5]: https://github.com/moby/moby/commit/96b29f5a1f7fc5e5d8b2b4dbd130e215bbb92ae9
[moby@7652f38]: https://github.com/moby/moby/commit/7652f38c289909bc61b1113c0570b9de345bbed9

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/volume/prune.go

@@ -11,7 +11,6 @@ import (
 	"github.com/docker/cli/internal/prompt"
 	"github.com/docker/cli/opts"
 	"github.com/docker/go-units"
-	"github.com/moby/moby/api/types/versions"
 	"github.com/spf13/cobra"
 )
 
@@ -72,16 +71,11 @@ func runPrune(ctx context.Context, dockerCli command.Cli, options pruneOptions)
 	pruneFilters := command.PruneFilters(dockerCli, options.filter.Value())
 
 	warning := unusedVolumesWarning
-	if versions.GreaterThanOrEqualTo(dockerCli.CurrentVersion(), "1.42") {
-		if options.all {
-			if _, ok := pruneFilters["all"]; ok {
-				return 0, "", invalidParamErr{errors.New("conflicting options: cannot specify both --all and --filter all=1")}
-			}
-			pruneFilters.Add("all", "true")
-			warning = allVolumesWarning
+	if options.all {
+		if _, ok := pruneFilters["all"]; ok {
+			return 0, "", invalidParamErr{errors.New("conflicting options: cannot specify both --all and --filter all=1")}
 		}
-	} else {
-		// API < v1.42 removes all volumes (anonymous and named) by default.
+		pruneFilters.Add("all", "true")
 		warning = allVolumesWarning
 	}
 	if !options.force {