Fix artifact tarball sha

[kshyatt]

tree hash also needed TLC. fixes #9

[IanButterworth]

Seems the MacOS tarballs have changed too

 Downloading artifact: micromamba-0.27.0
┌ Error: Hash Mismatch!
│   Expected sha256:   3c1a5ebb151668ce683fb74073bce5e01740663d5917769adb6d2703441b4531
│   Calculated sha256: 32eb83ad09f9c97c230793ef5572ee8cbcf425bcc3683b0035303867c11025aa
└ @ Pkg.PlatformEngines /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-macmini-x64-6.0/build/default-macmini-x64-6-0/julialang  Downloaded artifact: micromamba-0.27.0

Edit: I now see @giordano saying "and not just for this platform, but for all the other 0.27.0 builds" above

[jonashaag]

for all the other 0.27.0 builds

FYI, you may assume that this is typically the case if the build number changes. In the Conda ecosystem the "full version" is the tuple of (version, build number). The rationale of this is that version should always mirror the upstream's version number and the build number is the version of the build "scripts". For example here we fixed something in the build scripts of micromamba 0.27.0, bumping the build number: https://github.com/conda-forge/micromamba-feedstock/pull/96/files#diff-f3725a55bf339595bf865fec73bda8ac99f283b0810c205442021f29c06eea9a

[kshyatt]

Switched to the conda-forge urls mentioned above.

[giordano]

I verified the sha256 checksums, they look ok apart from the powerpc one (there was a typo in the URL).

CC @cjdoris it'd be nice to have a quick release including this fix

[IanButterworth]

Confirm this fixes MacOS

[IanButterworth]

bump

[cjdoris]

Apologies for the delay. Thanks for the PR, but I am going to use micromamba_jll to supply the executable, for guaranteed availability.