Bump micromamba to 1.3.1 to resolve unix installation issues

[hmaarrfk]

• Closes https://github.com/conda-forge/miniforge/issues/420
• Closes https://github.com/conda-forge/miniforge/issues/419
• Closes https://github.com/conda-forge/miniforge/pull/406

Checklist

• [ ] Used a personal fork of the feedstock to propose changes
• [ ] Bumped the build number (if the version is unchanged)
• [ ] Reset the build number to 0 (if the version changed)
• [ ] Re-rendered with the latest conda-smithy (Use the phrase code>@<space/conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• [ ] Ensured the license file is being packaged.

[hmaarrfk]

Needs https://github.com/conda-forge/micromamba-feedstock/pull/109