Add two additional PATH env checks for the rule 'os-04'

### Description

I suggest adding two checks for the rule 'os-04' for PATH environment variable:
- check that there are no spaces;
- check that there are no '..' (parent directory of the current one).

I guess it won't be superfluous.

### Solution

Can be easily solved as:
```
...
    its('split') { should_not include(' ') }
    its('split') { should_not include('..') }
...
```
