Bump PSModule/Invoke-Pester from 4.2.4 to 4.2.6 (#121)

Bumps
[PSModule/Invoke-Pester](https://github.com/PSModule/Invoke-Pester) from
**v4.2.4** to **v4.2.6** (latest).

Supersedes #115, which only bumped to v4.2.5 — going straight to the
latest avoids chaining two dependency PRs.

## What this PR changes

A single pin in [action.yml](action.yml):

```
uses: PSModule/Invoke-Pester@9cf262a # v4.2.6
```

Upstream changes inside Invoke-Pester between v4.2.4 and v4.2.6 are
captured in its own [release
notes](https://github.com/PSModule/Invoke-Pester/releases). Those (e.g.
its internal upload-artifact / GitHub-Script bumps) are internal to the
Invoke-Pester action, not separate dependencies of this repo.

## Status of all pinned actions in this repo

| Action | Pinned | Latest | Status |
| --- | --- | --- | --- |
| `actions/checkout` | v7.0.0 | v7.0.0 | up to date |
| `super-linter/super-linter` | v8.7.0 | v8.7.0 | up to date |
| `PSModule/Release-GHRepository` | v2.0.2 | v2.0.2 | up to date |
| `PSModule/Invoke-Pester` | v4.2.6 | v4.2.6 | **this PR** |
| `PSModule/Install-PSModuleHelpers` | v1.0.7 | v1.0.8 | handled by #119
|

Author: MariusStorhaug

action.yml

@@ -281,7 +281,7 @@ runs:
         ${{ github.action_path }}/src/main.ps1
 
     - name: Invoke-Pester
-      uses: PSModule/Invoke-Pester@abddf7bef0d0614d7ca322036af6a06ee0fb4d44 # v4.2.4
+      uses: PSModule/Invoke-Pester@9cf262a79e7528d5af41c875c35dae91c44d18dd # v4.2.6
       id: test
       env:
         LocalTestPath: ${{ steps.paths.outputs.LocalTestPath }}