Improve publish workflow

[teutoburg]

• Add improved version bump workflow action tested elsewhere.
• Improve build and publish workflow (painfully debugged elsewhere).

Again using this repo as a bit of a testbed.

[codecov[bot]]

Codecov Report

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

Comparison is base (dddd9a9) 75.34% compared to head (7061329) 75.34%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #45 +/- ## ======================================= Coverage 75.34% 75.34% ======================================= Files 3 3 Lines 365 365 ======================================= Hits 275 275 Misses 90 90 ```

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