chore(updater): move updater packages to pkg/updaters/<name>

pkg/updaters/mullvad/updater.go

@@ -0,0 +1,19 @@
+package mullvad
+
+import (
+	"net/http"
+)
+
+type Updater struct {
+	client *http.Client
+}
+
+func New(client *http.Client) *Updater {
+	return &Updater{
+		client: client,
+	}
+}
+
+func (u *Updater) Version() uint16 {
+	return 4 //nolint:mnd
+}