Fix linting results - part 1 - persist credentials and pinned GitHub Actions

[ArBridgeman]

To do #811, there are many steps.

As a start, issues found with the linter will be addressed in batched issues like this.
This issue will fix:

• persist credentials
• switching GitHub actions from v* to SHA # v* usage

To do this, we will

1. Add zizmor as a PTB dependency. This allows the developer to get the linting results locally and fix them.
   -> Maybe one day we'll add a nox sessions for it like zizmor:check and zizmor:fix
2. Add a zizmor.yml to ignore specific issues until they can be addressed. This will be in the GitHub directory so that it follows it can eventually be picked up a GitHub linting actions in checks.yml, like was tested in https://github.com/exasol/python-toolbox/pull/863/changes.
3. Batch together similar commits to reduce checking efforts.