Switch from Mambaforge to Miniforge

[pnuu]

The Mambaforge installer is deprecated, so lets switch to Miniforge.

• [ ] Closes #xxxx
• [ ] Tests added
• [ ] Tests passed
• [ ] Passes flake8 trollflow2
• [ ] Fully documented
• [ ] Add your name to AUTHORS.md if not there already

[codecov[bot]]

Codecov Report

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

Project coverage is 95.78%. Comparing base (cb4cab3) to head (d6a96a9). Report is 4 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #214 +/- ## ======================================= Coverage 95.78% 95.78% ======================================= Files 12 12 Lines 2989 2989 ======================================= Hits 2863 2863 Misses 126 126 ``` | [Flag](https://app.codecov.io/gh/pytroll/trollflow2/pull/214/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pytroll) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/pytroll/trollflow2/pull/214/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pytroll) | `95.78% <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=pytroll#carryforward-flags-in-the-pull-request-comment) to find out more.

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