CI: use local registry php image

Jenkinsfile

@@ -12,7 +12,7 @@ pipeline {
                 docker run --rm \
                     --workdir /app \
                     -v ${env.WORKSPACE}:/app \
-                    php:8.1-cli \
+                    registry.fakecake.org/php:8.1-cli \
                     php ./vendor/bin/phpunit
                 """
             }
@@ -24,7 +24,7 @@ pipeline {
                 docker run --rm \
                     --workdir /app \
                     -v ${env.WORKSPACE}:/app \
-                    php:8.1-cli \
+                    registry.fakecake.org/php:8.1-cli \
                     php -d memory_limit=-1 ./vendor/bin/phpstan --memory-limit=2G
                 """
             }