[Fix] (CI): treat a process that exits mid-read of its /proc stat as gone in the TCP server fixture

scripts/ci/tcp_server_fixture.py

@@ -16,7 +16,8 @@ from urllib.parse import urlsplit
 def process_start(pid):
     try:
         return Path(f'/proc/{pid}/stat').read_text().rsplit(')', 1)[1].split()[19]
-    except FileNotFoundError:
+    except (FileNotFoundError, ProcessLookupError):
+        # ESRCH: the process exited between opening its stat file and reading it.
         return None