Fix CI yaml example for Windows Shared Runners

What does this MR do?

The CI snippet as is didn't work and caused the job to fail with an error if run https://gitlab.com/erushton/windows-shared-runner/-/jobs/410786039

The new snippet fixes the error and runs successfully https://gitlab.com/erushton/windows-shared-runner/-/jobs/410801996

@marcel.amirault can you review this? Sorry for forgetting to prefix the branch name with docs- 😞

CC @tmaczukin @steveazz @DarrenEastman