Add gemini example using litellm #599

Job	Run time
find-tutorials	6s
test-00_sync/000_hello_acp	2m 26s
test-10_async/10_temporal/010_agent_chat	2m 47s
test-10_async/00_base/000_hello_acp	2m 23s
test-00_sync/020_streaming	2m 41s
test-10_async/00_base/010_multiturn	2m 26s
test-10_async/10_temporal/000_hello_acp	2m 20s
test-10_async/00_base/030_tracing	2m 21s
test-10_async/10_temporal/020_state_machine	2m 43s
test-00_sync/010_multiturn	2m 49s
test-10_async/00_base/020_streaming	2m 28s
test-10_async/00_base/040_other_sdks	3m 57s
test-10_async/10_temporal/030_custom_activities	2m 20s
test-10_async/10_temporal/070_open_ai_agents_sdk_tools	2m 18s
test-10_async/00_base/080_batch_events	2m 59s
test-10_async/10_temporal/080_open_ai_agents_sdk_human_in_the_loop	2m 32s
test-10_async/10_temporal/090_claude_agents_sdk_mvp	2m 11s
test-10_async/10_temporal/050_agent_chat_guardrails	2m 23s
test-10_async/10_temporal/060_open_ai_agents_sdk_hello_world	2m 30s
test-10_async/10_temporal/100_gemini_litellm	2m 16s
Test Summary	4s
	49m 0s

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