Upgrade symfony/dependency-injection

In Symfony before 2.7.51, 2.8.x before 2.8.50, 3.x before 3.4.26, 4.x
before 4.1.12, and 4.2.x before 4.2.7, when service ids allow user
input, this could allow for SQL Injection and remote code execution.

GHSA-pgwj-prpq-jpc2

CHANGELOG.md

@@ -1,5 +1,10 @@
 # CHANGELOG
 
+## Unreleased
+
+* Upgraded [symfony/dependency-injection](https://packagist.org/packages/symfony/dependency-injection) to avoid
+  [CVE-2019-10910](https://github.com/advisories/GHSA-pgwj-prpq-jpc2)
+
 ## 1.6.0 - 2019-11-09
 
 * Each Firebase SDK component is now individually registered and accessible ([#16](https://github.com/kreait/firebase-bundle/pull/16)).

composer.json

@@ -13,7 +13,7 @@
     ],
     "require": {
         "kreait/firebase-php": "^4.35",
-        "symfony/dependency-injection": "^2.8|^3.4|^4.0",
+        "symfony/dependency-injection": "^2.8.50|^3.4.26|^4.1.12",
         "symfony/config": "^2.8|^3.4|^4.0",
         "symfony/http-kernel": "^2.8|^3.4|^4.0"
     },