Update default model config

Signed-off-by: Kelly Abuelsaad <kaymar@gmail.com>

Author: kellyaa

a2a/git_issue_agent/.env.template

@@ -1,5 +1,5 @@
-TASK_MODEL_ID = "ollama/gpt-oss:20b"
-LLM_API_BASE = "http://localhost:11434"
+TASK_MODEL_ID = "ollama/ibm/granite4:latest"
+LLM_API_BASE = "http://host.docker.internal:11434"
 LLM_API_KEY = "ollama"
 MODEL_TEMPERATURE = 0
 MCP_URL = "https://api.githubcopilot.com/mcp/"