style: refactor codebase for improved consistency and clarity

- Reorder imports in `jenkins_test.go` and `plugin_test.go` to move `assert` import to the end
- Remove unnecessary empty line in `plugin.go`

Signed-off-by: appleboy <appleboy.tw@gmail.com>

jenkins_test.go

@@ -1,10 +1,10 @@
 package main
 
 import (
-	"github.com/stretchr/testify/assert"
-
 	"net/url"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestParseJobPath(t *testing.T) {

plugin.go

@@ -31,7 +31,6 @@ func trimElement(keys []string) []string {
 
 // Exec executes the plugin.
 func (p Plugin) Exec() error {
-
 	if len(p.BaseURL) == 0 || len(p.Username) == 0 || len(p.Token) == 0 {
 		return errors.New("missing jenkins config")
 	}

plugin_test.go

@@ -1,9 +1,9 @@
 package main
 
 import (
-	"github.com/stretchr/testify/assert"
-
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestMissingConfig(t *testing.T) {