Add missing env in install.sh

Fix https://github.com/wallabag/wallabag/issues/2345

diff --git a/install.sh b/install.sh
index 87d53bf09e7f3b4a822c7492cf75c6ce06c62704..fad8b4c092c0119ac444c9c39f7def63322431f6 100755 (executable)
--- a/install.sh
+++ b/install.sh
@@ -1,7 +1,7 @@
 #! /usr/bin/env bash
 
 echo " > Installing PHP dependencies through Composer..."
-composer install --no-interaction --no-progress --prefer-dist -o --no-dev
+SYMFONY_ENV=prod composer install --no-interaction --no-progress --prefer-dist -o --no-dev
 
 chmod ugo+x vendor/mouf/nodejs-installer/bin/local/npm
 echo " > Downloading librairies through npm..."