Fix environment variable format in backend.env

Author: ajeetraina

backend.env

@@ -1,9 +1,9 @@
-BASE_URL: http://model-runner.docker.internal/engines/llama.cpp/v1/
-MODEL: ai/llama3.2:1B-Q8_0
-API_KEY: ${API_KEY:-dockermodelrunner}
+BASE_URL=http://model-runner.docker.internal/engines/llama.cpp/v1/
+MODEL=ai/llama3.2:1B-Q8_0
+API_KEY=${API_KEY:-dockermodelrunner}
 
 # Observability configuration
-LOG_LEVEL: info
-LOG_PRETTY: true
-TRACING_ENABLED: true
-OTLP_ENDPOINT: jaeger:4318
+LOG_LEVEL=info
+LOG_PRETTY=true
+TRACING_ENABLED=true
+OTLP_ENDPOINT=jaeger:4318