[Bug]: Error changing configuration type

[jvstme]

Steps to reproduce

1. Create and run a configuration with a name.

   > cat .dstack.yml
   name: test-1
   type: dev-environment
   ide: vscode
   
   > dstack apply -y

2. Stop the run.
3. Change the configuration type and re-run.

   > cat .dstack.yml
   name: test-1
   type: task
   commands:
   - sleep infinity
   
   > dstack apply -y

Actual behaviour

CLI:

Traceback (most recent call last):
  File "/home/jvstme/git/dstack/dstack/venv/bin/dstack", line 8, in <module>
    sys.exit(main())
  File "/home/jvstme/git/dstack/dstack/src/dstack/_internal/cli/main.py", line 81, in main
    args.func(args)
  File "/home/jvstme/git/dstack/dstack/src/dstack/_internal/cli/commands/apply.py", line 77, in _command
    configurator.apply_configuration(
  File "/home/jvstme/git/dstack/dstack/src/dstack/_internal/cli/services/configurators/run.py", line 104, in apply_configuration
    diff = diff_models(
  File "/home/jvstme/git/dstack/dstack/src/dstack/_internal/core/services/diff.py", line 9, in diff_models
    raise TypeError("Both instances must be of the same Pydantic model class.")
TypeError: Both instances must be of the same Pydantic model class.

Expected behaviour

The new configuration runs successfully.

dstack version

0.18.27

Server logs

No response

Additional information

No response