use php 7.3 for special tests

Author: dbu

.travis.yml

@@ -21,7 +21,7 @@ matrix:
     fast_finish: true
     include:
           # Minimum supported Symfony version and latest PHP version
-        - php: 7.2
+        - php: 7.3
           env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest" SYMFONY_DEPRECATIONS_HELPER="weak" SYMFONY_PHPUNIT_VERSION="5.7"
 
           # Test the latest stable release
@@ -36,15 +36,15 @@ matrix:
           env: COVERAGE=true TEST_COMMAND="composer test-ci"
 
           # Test LTS versions
-        - php: 7.2
+        - php: 7.3
           env: DEPENDENCIES="dunglas/symfony-lock:^2"
-        - php: 7.2
+        - php: 7.3
           env: DEPENDENCIES="dunglas/symfony-lock:^3"
-        - php: 7.2
+        - php: 7.3
           env: DEPENDENCIES="dunglas/symfony-lock:^4"
 
           # Latest commit to master
-        - php: 7.2
+        - php: 7.3
           env: STABILITY="dev"
 
     allow_failures: