🩹 [Patch]: Install built modules at their real version (bump Install-PSModuleHelpers) (#52)

## What

`Document-PSModule` installs the built module (via `Install-PSModule`
from `Install-PSModuleHelpers`) before generating docs. That helper used
to copy the module into a hard-coded `999.0.0` folder, which breaks now
that
[Process-PSModule#326](PSModule/Process-PSModule#326)
stamps the real version at build time (folder no longer matches the
manifest, so `Import-Module` fails and `Build-Docs` breaks).

## Change

Bump the `Install-PSModuleHelpers` pin to the version that installs into
a folder matching the manifest `ModuleVersion`
([PSModule/Install-PSModuleHelpers#19](PSModule/Install-PSModuleHelpers#19)).

> **Pinned to the released tag:**
[PSModule/Install-PSModuleHelpers#19](PSModule/Install-PSModuleHelpers#19)
is merged and released, so this now pins
[`v1.0.8`](https://github.com/PSModule/Install-PSModuleHelpers/releases/tag/v1.0.8).

Part of the
[Process-PSModule#326](PSModule/Process-PSModule#326)
refactor.

Author: MariusStorhaug

action.yml

@@ -19,7 +19,7 @@ runs:
   using: composite
   steps:
     - name: Install-PSModuleHelpers
-      uses: PSModule/Install-PSModuleHelpers@ed79b6e3aa8c9cd3d30ab2bf02ea6bd4687b9c74 # v1.0.7
+      uses: PSModule/Install-PSModuleHelpers@68e8ca76be679bfcb7099aed8cffa911c4ab72af # v1.0.8
 
     - name: Document-PSModule
       shell: pwsh