E2E tests use repeated strings for test data where constants add no value (#97)

---------

Co-authored-by: Pasha Sviderski <me@psviderski.name>
Co-authored-by: Anton Ovchinnikov <anton@tonyo.info>

pkg/client/caddy_test.go

@@ -1,10 +1,11 @@
 package client
 
 import (
+	"testing"
+
 	"github.com/distribution/reference"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-	"testing"
 )
 
 func TestLatestCaddyImage(t *testing.T) {