[Yaml] Deprecate tags using colon

Author: GuilhemN

Tests/Mapping/Loader/mapping-with-constants.yml

@@ -5,4 +5,4 @@ Symfony\Component\Validator\Tests\Fixtures\Entity:
   properties:
     firstName:
       - Range:
-          max: !php/const:PHP_INT_MAX
+          max: !php/const PHP_INT_MAX

composer.json

@@ -25,7 +25,7 @@
         "symfony/http-kernel": "^3.3.5|~4.0",
         "symfony/var-dumper": "~3.3|~4.0",
         "symfony/intl": "^2.8.18|^3.2.5|~4.0",
-        "symfony/yaml": "~3.3|~4.0",
+        "symfony/yaml": "~3.4|~4.0",
         "symfony/config": "~2.8|~3.0|~4.0",
         "symfony/dependency-injection": "~3.3|~4.0",
         "symfony/expression-language": "~2.8|~3.0|~4.0",
@@ -39,7 +39,7 @@
         "phpunit/phpunit": "<4.8.35|<5.4.3,>=5.0",
         "symfony/dependency-injection": "<3.3",
         "symfony/http-kernel": "<3.3.5",
-        "symfony/yaml": "<3.3"
+        "symfony/yaml": "<3.4"
     },
     "suggest": {
         "psr/cache-implementation": "For using the metadata cache.",