This fixes the problem of zopen list/zopen install not pulling in the latest releases because zopen_releases.json is not getting updated.
With the change to use https://raw.githubusercontent.com/ZOSOpenTools/meta/main/docs/api/zopen_releases.json, it seems that the "Last modified" http header is removed. So we now use ETag instead: https://en.wikipedia.org/wiki/HTTP_ETag . I verified that the ETag changes once zopen_releases.json is updated.
The PR also check if ETag exists, and if it doesn't download the zopen_releases.json cache
I'll add a subsequent test in metaport to ensure ETag is present
https://raw.githubusercontent.com/ZOSOpenTools/meta/main/docs/api/zopen_releases.json, it seems that the "Last modified" http header is removed. So we now use ETag instead: https://en.wikipedia.org/wiki/HTTP_ETag . I verified that the ETag changes once zopen_releases.json is updated.I'll add a subsequent test in metaport to ensure ETag is present