Fix threshold field in Codecov configuration and un-ignore modules

[mkniewallner]

PR Checklist

• A description of the changes is added to the description of this PR.
• If there is a related issue, make sure it is linked to this PR.
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated

Description of changes

Checking Codecov shows that the configuration is correctly invalid, as shown by https://app.codecov.io/gh/fpgmaas/deptry/commit/a701a5ae931d5d3f0dc59abc797b871b39009879.

Using the method described in https://docs.codecov.com/docs/codecov-yaml#validate-your-repository-yaml to validate the configuration:

$ curl -sSL --fail-with-body --data-binary @codecov.yaml https://codecov.io/validate
Error at ['coverage', 'status', 'project', 'default', 'threshold']: 
field 'threshold' cannot be coerced: 
curl: (22) The requested URL returned error: 400

With the change:

$ curl -sSL --fail-with-body --data-binary @codecov.yaml https://codecov.io/validate
Valid!

{
  "coverage": {
    "range": [
      70.0,
      100.0
    ],
    "round": "down",
    "precision": 1,
    "status": {
      "project": {
        "default": {
          "target": 90.0,
          "threshold": 0.5
        }
      }
    }
  }
}

Figured we could also un-ignore the modules currently ignored, since this will force us to add tests if coverage is not enough in those modules.

Also see #144 that suggests to add a CI workflow to ensure that the configuration is not broken on updates.