fixing the logic to fetch the sha value from the correct file

[soninaren]

Issue

The feed generation logic was updated to add v0 tags for net 8 inproc. Below is sample of the value of the core tools property. Here the SHA value mentioned in the property is actually for file https://functionscdn.azureedge.net/public/4.0.5858/Azure.Functions.Cli.win-x86.4.0.5858.zip. The updated logic had failed to take into account _net8 string added to the name and was reading the incorrect sha value.

{
    "OS": "Windows",
    "Architecture": "x86",
    "downloadLink": "https://functionscdn.azureedge.net/public/4.0.5858/Azure.Functions.Cli.win-x86_net8.4.0.5858.zip",
    "sha2": "448ec30de82f04caebd46f238280c4d104ffaf4b5da97a9bd6d24a391ef831ce",
    "size": "full",
    "default": "false"
}

Fix

The PR takes into account _net8 string addition to the file name and reads the correct value.