numcodecs pickle codec security advisory #4539

numcodecs issued a security advisory concerning the possibility that an attacker can leverage the pickle codec decode method to run arbitrary code on a target. see GHSA-jqc8-qjfv-5m6r. To mitigate this we patched numcodecs and cut 3 releases: 0.17.1, 0.16.6, and 0.15.2

For zarr, I propose the following steps:

• we bump our numcodecs min to 0.16.6
• we add runtime code that refuses the pickle codec unless the user opts in explicitly. i think there's a PR up already that does this
• we issue a 2.x patch release that bumps the minimum numcodecs version to 0.15.2, for folks who haven't upgraded yet

lmk if anyone wants to help with this, otherwise I can take it on