The maximum value for `ATTEN_RESULTS_TIMEOUT` is 1050. Trying a higher
number cause an error:

```
pyslac-slac-1  | DEBUG:asyncio:Using selector: EpollSelector
pyslac-slac-1  | Traceback (most recent call last):
pyslac-slac-1  |   File "/venv/lib/python3.10/site-packages/pyslac/examples/single_slac_session.py", line 93, in <module>
pyslac-slac-1  |     run()
pyslac-slac-1  |   File "/venv/lib/python3.10/site-packages/pyslac/examples/single_slac_session.py", line 89, in run
pyslac-slac-1  |     asyncio.run(main())
pyslac-slac-1  |   File "/usr/local/lib/python3.10/asyncio/runners.py", line 44, in run
pyslac-slac-1  |     return loop.run_until_complete(main)
pyslac-slac-1  |   File "/usr/local/lib/python3.10/asyncio/base_events.py", line 641, in run_until_complete
pyslac-slac-1  |     return future.result()
pyslac-slac-1  |   File "/venv/lib/python3.10/site-packages/pyslac/examples/single_slac_session.py", line 77, in main
pyslac-slac-1  |     slac_config.load_envs(env_path)
pyslac-slac-1  |   File "/venv/lib/python3.10/site-packages/pyslac/environment.py", line 47, in load_envs
pyslac-slac-1  |     env.seal()  # raise all errors at once, if any
pyslac-slac-1  |   File "/venv/lib/python3.10/site-packages/environs/__init__.py", line 447, in seal
pyslac-slac-1  |     raise EnvValidationError(f"Environment variables invalid: {error_messages}", error_messages)
pyslac-slac-1  | environs.EnvValidationError: Environment variables invalid: {'ATTEN_RESULTS_TIMEOUT': ['Must be less than or equal to 1050.']}
```g