Fix capitalization cases for PoshChan

[RDIL]

PR Summary

The jobs name is fully lowercase
Fixes the issue found by @iSazonov

PR Context

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Change is not breaking
• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
• This PR is ready to merge and is not Work in Progress.
  • If the PR is work in progress, please add the prefix WIP: or [ WIP ] to the beginning of the title (the WIP bot will keep its status check at Pending while the prefix is present) and remove the prefix when the PR is ready.
• User-facing changes
  • Not Applicable
  • OR
  • Documentation needed
    • Issue filed:
• Testing - New and feature
  • N/A or can only be tested interactively
  • OR
  • Make sure you've added a new test if existing tests do not effectively test the code changed
    • Add [feature] to your commit messages if the change is significant or affects feature tests

[iSazonov]

The same for "linux"

@SteveL-MSFT Can it be case-insensetive?

[SteveL-MSFT]

@PoshChan Please rebuild mAcOS

[PoshChan]

@SteveL-MSFT, could not find a matching build target

[RDIL]

@SteveL-MSFT typo

[SteveL-MSFT]

@RDIL testing case-insensitivity which is what I expected

[RDIL]

Oh

[SteveL-MSFT]

Intent was to be case-insensitive, but forgot that ConvertFrom-Json -AsHashTable results in a case-sensitive hashtable. I believe I can fix this on the server side.

[SteveL-MSFT]

@PoshChan-Staging Please rebuild MACos

[PoshChan-Staging]

@SteveL-MSFT, successfully started rebuild of PowerShell-CI-macOS

[SteveL-MSFT]

@PoshChan please rebuild linux

[PoshChan]

@SteveL-MSFT, all requests start with the magic word Please.

[RDIL]

lol

[SteveL-MSFT]

@PoshChan-Staging please rebuild LINux

[PoshChan-Staging]

@SteveL-MSFT, successfully started rebuild of PowerShell-CI-Linux

[SteveL-MSFT]

@PoshChan pLeASE rEbuild wINDOws

[PoshChan]

@SteveL-MSFT, successfully started rebuild of PowerShell-CI-windows

[SteveL-MSFT]

Ok, I believe @PoshChan is fully case-insensitive now :)

So, this PR isn't necessary except for aesthetic reasons. But then you might as well fix Windows, macOS, and Linux with "correct" casing :)