Ensure tag-exists works as intended

[frederikprijck]

Changes

The tag-exists action was not working due to the fact that it was trying to read from a step that did not exist. Without these changes, it would always 404 and act as if the tag doesn't exist.

Checklist

• [x] I have read the Auth0 general contribution guidelines
• [x] I have read the Auth0 Code of Conduct
• [x] All code quality tools/guidelines have been run/followed

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (957c786) 100.00% compared to head (e96724c) 100.00%. Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #752 +/- ## =========================================== Coverage 100.00% 100.00% Complexity 1381 1381 =========================================== Files 62 62 Lines 4776 4776 =========================================== Hits 4776 4776 ``` | [Flag](https://app.codecov.io/gh/auth0/auth0-PHP/pull/752/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=auth0) | Coverage Δ | | |---|---|---| | [unittestsvalidate](https://app.codecov.io/gh/auth0/auth0-PHP/pull/752/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=auth0) | `100.00% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=auth0#carryforward-flags-in-the-pull-request-comment) to find out more.

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