mypy shows stale results

@karthiknadig is already working on this.

Since Nov 29, 2023.

For some reason, I find that the type-checker extension is showing stale results in the editor. But when I go to the output window and run the command that is being logged in my own shell, I get the correct and expected answer. This seems to happen when changes are made in another file than the one being viewed/edited.

For example:

```
2023-11-28 12:32:47.671 [info] /.../mypy --no-color-output --no-error-summary --show-absolute-path --show-column-numbers --show-error-codes --no-pretty --config-file=/.../mypy.ini --cache-dir=/.../mypy_cache --show-error-end /.../my-file.py
2023-11-28 12:32:47.671 [info] CWD Server: /.../src
2023-11-28 12:32:56.431 [info] file:///... :
/.../my-file:102:35:102:62: error: "Base" has no attribute "get_slack_instructions" [attr-defined]
/.../my-file.py:103:42:103:69: error: "Base" has no attribute "get_slack_instructions" [attr-defined]
```

```
user@host1:/.../src 2023-11-28 12:33:34
% /.../mypy --no-color-output --no-error-summary --show-absolute-path --show-column-numbers --show-error-codes --no-pretty --config-file=/.../mypy.ini --cache-dir=/.../mypy_cache --show-error-end /.../my-file.py

% # (no error)
```

Using `v2023.7.13181008` (latest pre-release), with the settings:
```
"mypy-type-checker.args": [
"--config-file=${workspaceFolder}/mypy.ini",
"--cache-dir=/.../mypy_cache"
],
"mypy-type-checker.importStrategy": "fromEnvironment",
"mypy-type-checker.preferDaemon": false,
"mypy-type-checker.path": [
"/.../mypy"
],
```
And my `mypy-type-checker` points to the mypy in the python venv set for the project.