Remove demo gif from README #5262

Job	Run time
build-and-check	2m 41s
test-packages/agent-runtime	1m 1s
test-.agents	38s
test-packages/internal	43s
test-cli	1m 10s
test-packages/billing	34s
test-common	43s
test-integration-.agents	45s
test-web	42s
test-integration-packages/billing	40s
test-integration-sdk	40s
test-integration-common	38s
test-integration-cli	42s
test-integration-web	41s
test-integration-packages/agent-runtime	38s
test-sdk	51s
test-integration-packages/internal	39s
	14m 26s

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