fix: add missing strings import in version_filter_test.go

The containsNonComment helper uses strings.Split and strings.TrimSpace
but the import was missing. Only visible with -tags=integration.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ako

mdl/executor/version_filter_test.go

@@ -5,6 +5,7 @@
 package executor
 
 import (
+	"strings"
 	"testing"
 
 	"github.com/mendixlabs/mxcli/sdk/mpr/version"