error : "Could not open input file: analyze"

Hi,

Thank you for your work on this package.

I'm been using spacemacs (develop branch) and phpstan separately for some time, but after having discovered this package, I wanted to give it a try.

I tried with phpstan installed globally and falled back to docker, but had the same error on both attempts

```
Suspicious state from syntax checker phpstan: Flycheck checker phpstan returned non-zero exit code 1, but its output contained no errors: Could not open input file: analyze
```

Can that error message tell what is wrong with my setup ?

I'm using this in .dir-locals.el

```
((nil . ((php-project-root . git)
(phpstan-executable . docker)
(phpstan-working-dir . (root . "."))
(phpstan-config-file . (root . "./phpstan.neon"))
(phpstan-level . 7))))
```

Then, I've begun a private php layer where I initialize some things and which could contain the source of this error, but it is more a spacemacs thing so I'lle leave it out for now.

Inspect the phpstan checker command construction and compare it with the .dir-locals.el settings for phpstan-executable, phpstan-working-dir, and phpstan-config-file. Reproduce the global and Docker configurations, then confirm the checker no longer treats "analyze" as an input file and reports PHPStan diagnostics normally.

Written by the indexing model from the issue text.