fix(service_manager): pass encoding to Path.read_text in _s6_running

PR #30136 CI: ruff PLW1514 (preview rule unspecified-encoding) failed on
`Path('/proc/1/comm').read_text().strip()` introduced by commit
2f8ceeab9 (the daimon-nous critical-bug fix that switched s6 detection
off /proc/1/exe to /proc/1/comm so it works for the unprivileged hermes
user).

Add explicit encoding='utf-8'. /proc/1/comm is always plain ASCII (the
kernel's PR_GET_NAME / TASK_COMM_LEN buffer), so utf-8 is correct and
locale-independent.

hermes_cli/service_manager.py

@@ -143,7 +143,7 @@ def _s6_running() -> bool:
     init, or an unrelated process named ``s6-svscan``).
     """
     try:
-        comm = Path("/proc/1/comm").read_text().strip()
+        comm = Path("/proc/1/comm").read_text(encoding="utf-8").strip()
     except OSError:
         return False
     if comm != "s6-svscan":