Buildkite CLI 3.46.0

Changelog

• daa9201: feat: add shm credential store for headless auth (@lox)
• f9123eb: fix: harden shm credential store selection (@lox)
• 60e3661: fix: delete stale shm credentials after keyring writes (@lox)
• f2e3277: fix: align login credential store selection (@lox)
• d4d04f0: fix: clear stale refresh credentials (@lox)
• 0aa427b: refactor: simplify credential cleanup (@lox)
• b88a8ae: refactor: route credentials through store backends (@lox)
• 464c761: fix(deps): update buildkite to v5 (#848) (@renovate[bot])
• 60d98d4: Merge pull request #849 from buildkite/lox/auth-login-shm-store (@stephanieatte)