Fix release file attachments

softprops/action-gh-release globing doesn't support backslashes as
directory separators and instead always treats them as the an escape
character when a glob-based input under 'files' is detected.

Because of this, have the release job run on ubuntu so that the
zip artifact directory path environment variable declared at the
workflow level will resolve to a path with forward slashes, since
environment variables are only evaluated at the job level.

See: softprops/action-gh-release#280

.github/workflows/master-pull-request-merge-reaction.yml

@@ -83,13 +83,14 @@ jobs:
     name: Create GitHub release
     needs: [update-docs, build_qx_release_windows, build_qx_release_linux, tag_master_and_sync_dev]
     if: github.event.pull_request.merged == true
-    runs-on: windows-latest
+    runs-on: ubuntu-latest
     steps:
     - name: Download built Qx artifacts
       uses: actions/download-artifact@v3
       with:
         path: ${{ env.artifacts_path }}
     - name: Zip up release artifacts
+      shell: pwsh
       run: |
         $artifact_folders = Get-ChildItem -Directory -Path "${{ env.artifacts_path }}"
         foreach($art_dir in $artifact_folders)