Test with php 7.3

.travis.yml

@@ -1,12 +1,19 @@
 language: php
+sudo: required
+dist: xenial
 php:
   - 5.5
   - 5.6
   - 7.0
   - 7.1
   - 7.2
+  - 7.3snapshot
 
-sudo: false
+addons:
+  apt:
+    packages:
+      # required for php7.3
+      - libzip4
 
 script:
   - ./bin/phpunit --configuration tests/phpunit.xml
@@ -18,3 +25,7 @@ before_script:
 cache:
   directories:
     - $HOME/.composer/cache
+
+matrix:
+  allow_failures:
+    - php: 5.5

lib/Component/VCard.php

@@ -511,7 +511,7 @@ function xmlSerialize(Xml\Writer $writer) {
                 switch ($property->name) {
 
                     case 'VERSION':
-                        continue;
+                        break;
 
                     case 'XML':
                         $value = $property->getParts();

lib/FreeBusyGenerator.php

@@ -430,7 +430,7 @@ protected function calculateBusy(FreeBusyData $fbData, array $objects) {
                                 // instance. We are skipping this event from the output
                                 // entirely.
                                 unset($this->objects[$key]);
-                                continue;
+                                break;
                             }
 
                             if ($this->start) {

tests/VObject/BirthdayCalendarGeneratorTest.php

@@ -475,11 +475,11 @@ function testVcardStringWithEmptyBirthdayProperty() {
     function testParseException() {
 
         $generator = new BirthdayCalendarGenerator();
-        $input = <<<FOO
+        $input = <<<EOT
 BEGIN:FOO
 FOO:Bar
 END:FOO
-FOO;
+EOT;
 
         $generator->setObjects($input);