Fixed architecture detection test on ci appveyor

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Related tickets | 
| License       | GNU GPLv3

The `cyg-apt update` command must be executed with the tested Python.

- [x] Merge #37
- [x] Wait for appveyor response ... [OK](https://ci.appveyor.com/project/alquerci/cyg-apt/build/1.0.102)
- [x] Revert #37