chore: modernize the codebase using go 1.26 (#278)

This runs:

```
go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -fix ./...
```

over the codebase, as this is using go 1.26, it can also use the new
new() functionallity so AsPtr and boolPtr is are needed anymore.

Signed-off-by: Miek Gieben <miek@miek.nl>

pkg/client/compose/service.go

@@ -346,9 +346,7 @@ func dockerVolumeSpecFromCompose(serviceVolume types.ServiceVolumeConfig, volume
 func mergeLabels(labels ...types.Labels) types.Labels {
 	merged := types.Labels{}
 	for _, l := range labels {
-		for k, v := range l {
-			merged[k] = v
-		}
+		maps.Copy(merged, l)
 	}
 	return merged
 }