add support of multiple values in host label

- example of usage:
  host('prod.example.org')
      ->set('hostname', 'example.cloud.google.com');
      ->setLabel(
          'state' => 'prod'
          'role' => ['build','web','redis']
      ]);

  host('prod-db.example.org')
        ->set('hostname', 'example.cloud.google.com');
        ->setLabel(
            'state' => 'prod'
            'role' => ['db']
        ]);
  host('qa.example.org')
      ->set('hostname', 'example.cloud.google.com');
      ->setLabel(
          'state' => 'qa'
          'role' => ['build','web','redis','db']
      ]);
  host('dev.example.org')
        ->set('hostname', 'example.cloud.google.com');
        ->setLabel(
            'state' => 'qa'
            'role' => ['build','web','redis','db']
        ]);
  ...

  desc('Clear pagespeed');
  task('pagespeed:clear', function () {
      run("rm -rf {{deploy_path}}/{{pagespeed_path}}* || true");
  })->select('stage=prod|qa & role=web'); // assuming pagespeed is installed only on prod and qa envs

src/Host/Host.php

@@ -212,6 +212,13 @@ public function setLabels(array $labels): self
         return $this;
     }
 
+    public function addLabels(array $labels): self
+    {
+        $existingLabels = $this->getLabels() ?? [];
+        $this->setLabels(array_replace_recursive($existingLabels, $labels));
+        return $this;
+    }
+
     public function getLabels(): ?array
     {
         return $this->config->get('labels', null);

src/Selector/Selector.php

@@ -57,7 +57,16 @@ public static function apply(?array $conditions, Host $host): bool
         foreach ($conditions as $hmm) {
             $ok = [];
             foreach ($hmm as list($op, $var, $value)) {
-                $ok[] = self::compare($op, $labels[$var] ?? null, $value);
+                if (is_array($value)) {
+                    $orOk = [];
+                    foreach ($value as $val) {
+                        $orOk[] = self::compare($op, $labels[$var] ?? null, $val);
+                    }
+                    $ok[] = count(array_filter($orOk, $isTrue)) > 0;
+                } else {
+                    $ok[] = self::compare($op, $labels[$var] ?? null, $value);
+                }
+
             }
             if (count($ok) > 0 && array_all($ok, $isTrue)) {
                 return true;
@@ -102,7 +111,8 @@ public static function parse(string $expression): array
                     continue;
                 }
                 if (preg_match('/(?<var>.+?)(?<op>!?=)(?<value>.+)/', $part, $match)) {
-                    $conditions[] = [$match['op'], trim($match['var']), trim($match['value'])];
+                    $values = array_map('trim', explode('|', trim($match['value'])));
+                    $conditions[] = [$match['op'], trim($match['var']), $values];
                 } else {
                     $conditions[] = ['=', 'alias', trim($part)];
                 }