fix: correct YAML syntax in build-docker-compose.yaml

Add missing environment key before CASC_RELOAD_TOKEN variable in
jenkins_controller service. This resolves YAML parsing errors that
were preventing updatecli from processing the file correctly.

Author: gounthar

build-docker-compose.yaml

@@ -45,6 +45,7 @@ services:
     build: dockerfiles/.
     restart: on-failure
     # The CASC_RELOAD_TOKEN environment variable is used by the Jenkins controller to restart the Configuration as Code (JCasc) plugin configuration.
+    environment:
       - CASC_RELOAD_TOKEN=thisisnotsecure
     ports:
       - "8080:8080"