Update backend.env

Author: ajeetraina

backend.env

@@ -1,3 +1,3 @@
 BASE_URL: http://model-runner.docker.internal/engines/llama.cpp/v1/
 MODEL: ai/llama3.2:1B-Q8_0
-API_KEY: ${API_KEY:-modelrunner}
+API_KEY: ${API_KEY:-dockermodelrunner}