fix: rename Devices.Rigetti.Cepheus1 to Cepheus1108Q to match device name

[jheckey]

Description

Renames the Devices.Rigetti.Cepheus1 enum member to Devices.Rigetti.Cepheus1108Q to match the actual device name Cepheus-1-108Q.

The previous name Cepheus1 was inconsistent with the device ARN (rigetti/Cepheus-1-108Q) and the naming convention used by other devices in the SDK.

Testing

• Linters pass (tox -e linters)
• Unit tests pass (34 device tests, 221 emulation tests)
• No tests reference the enum by name — all test fixtures use ARN strings directly

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (41fcb63) to head (8b5564d).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1241   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          169       169           
  Lines        10935     10935           
  Branches      1407      1407           
=========================================
  Hits         10935     10935           

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