[TESTS] Use vendor/bin/simple-phpunit for running the tests, as it provides the appropriate polyfills

docker/testing/coverage.sh

@@ -4,7 +4,7 @@ cd /var/www/social || exit 65
 
 yes yes | php bin/console doctrine:fixtures:load || exit 65
 
-if runuser -u www-data -- bin/phpunit --coverage-html .test_coverage_report; then
+if runuser -u www-data -- vendor/bin/simple-phpunit -vvv --coverage-html .test_coverage_report; then
     exit 64
 else
     exit 65

docker/testing/docker-compose.yaml

@@ -32,6 +32,8 @@ services:
     redis:
         image: redis:alpine
         tty: false
+        ports:
+          - 6379:6379
 
 volumes:
     database: