VPN Unlimited support (#499)

- Fixes #420 
- Revert to docker/build-push-action@v2.4.0

internal/updater/updater.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/qdm12/gluetun/internal/configuration"
+	"github.com/qdm12/gluetun/internal/constants"
 	"github.com/qdm12/gluetun/internal/models"
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 	"github.com/qdm12/gluetun/internal/updater/unzip"
@@ -186,6 +187,16 @@ func (u *updater) UpdateServers(ctx context.Context) (allServers models.AllServe
 		}
 	}
 
+	if u.options.VPNUnlimited {
+		u.logger.Info("updating " + constants.VPNUnlimited + " servers...")
+		if err := u.updateVPNUnlimited(ctx); err != nil {
+			if ctxErr := ctx.Err(); ctxErr != nil {
+				return allServers, ctxErr
+			}
+			u.logger.Error(err)
+		}
+	}
+
 	if u.options.Vyprvpn {
 		u.logger.Info("updating Vyprvpn servers...")
 		if err := u.updateVyprvpn(ctx); err != nil {