allow symfony/options-resolver 4.0

Author: fbourigault

.travis.yml

@@ -6,15 +6,17 @@ php:
   - 5.6
   - 7.0
   - 7.1
+  - 7.2
 
 matrix:
+  # test latest PHP stable version with lowest dependencies and phpstan static analysis
   include:
-    - php: 7.2
-      env: STATIC_ANALYSIS=yes
+    - php: 7.1
+      env: COMPOSER_FLAGS="--prefer-lowest" STATIC_ANALYSIS=yes
 
 before_script:
   - travis_retry composer self-update
-  - travis_retry composer install --no-interaction --prefer-source
+  - travis_retry composer install --no-interaction ${COMPOSER_FLAGS}
   - if [ "$STATIC_ANALYSIS" != "" ]; then curl -L https://github.com/phpstan/phpstan/releases/download/0.8/phpstan.phar -o phpstan.phar; fi;
 
 script:

composer.json

@@ -28,7 +28,7 @@
 		"php-http/discovery": "^1.2",
 		"php-http/httplug": "^1.1",
 		"php-http/multipart-stream-builder": "^1.0",
-		"symfony/options-resolver": "^2.6 || ^3.0"
+		"symfony/options-resolver": "^2.6 || ^3.0 || ^4.0"
 	},
 	"require-dev": {
 		"guzzlehttp/psr7": "^1.2",