chore: use gofumpt for code formatting

internal/provider/example/updater/api.go

@@ -8,9 +8,7 @@ import (
 	"net/http"
 )
 
-var (
-	errHTTPStatusCodeNotOK = errors.New("HTTP status code not OK")
-)
+var errHTTPStatusCodeNotOK = errors.New("HTTP status code not OK")
 
 type apiData struct {
 	Servers []apiServer `json:"servers"`
@@ -26,7 +24,8 @@ type apiServer struct {
 }
 
 func fetchAPI(ctx context.Context, client *http.Client) (
-	data apiData, err error) {
+	data apiData, err error,
+) {
 	// TODO: adapt this URL and the structures above to match the real
 	// API models you have.
 	const url = "https://example.com/servers"

internal/provider/example/updater/servers.go

@@ -11,7 +11,8 @@ import (
 )
 
 func (u *Updater) FetchServers(ctx context.Context, minServers int) (
-	servers []models.Server, err error) {
+	servers []models.Server, err error,
+) {
 	// FetchServers obtains information for each VPN server
 	// for the VPN service provider.
 	//

internal/provider/example/updater/updater.go

@@ -15,7 +15,8 @@ type Updater struct {
 }
 
 func New(warner common.Warner, unzipper common.Unzipper,
-	client *http.Client, parallelResolver common.ParallelResolver) *Updater {
+	client *http.Client, parallelResolver common.ParallelResolver,
+) *Updater {
 	// TODO: remove arguments not used by the updater
 	return &Updater{
 		client:           client,