Keychain 3.0.10

Keychain 3.0.10 fixes a macOS startup regression introduced in 3.0.9.

• macOS can display some process owners, including nobody, as negative user IDs. Keychain's stricter process-list validation rejected these legitimate entries, aborting startup even when the process was unrelated to your SSH agent. Keychain now interprets these IDs correctly on macOS, without relaxing process-ID validation or changing discovery on other platforms (#279).
• Added regression tests and a live macOS test covering agent startup, reuse and shutdown while a nobody process is running.

Thanks to David Harrigan (@dharrigan) for reporting the regression and @asterbini for identifying the signed-ID parsing problem.