o3-mini high available to Enterprise customers

OpenAI's latest cost-efficient reasoning model o3-mini was announced last month, and in Sourcegraph 6.1 we are making o3-mini-high available to all Enterprise Starter and Enterprise customers.

o3-mini is purported to be OpenAI's "highest performing released model on SWEbench-verified" for software engineering tasks, and we're excited to provide access to this model to customers.