Add missing apostrophe to WorkflowException message

[brempusz]

What was changed

Add missing apostrophe to WorkflowException message

Why?

Because the formatting was wrong

[CLAassistant]

All committers have signed the CLA.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[mjameswh]

@brempusz Can you please sign the CLA? We can't examine your PR until that has been cleared.

[brempusz]

I did it right after creating the pr but there is something wrong - I see two comments: 1st with information that all commiters signed the CLA and green checkmark and 2nd with yellow checkmark and signing instruction. I tried to sign it again. I tried to "recheck" the status. Nothing works...

[brempusz]

After some googling I followed a random recommendation on the net and rebased / pushed the PR again (it may refresh cla status on the commit).
In the checks i see:

It is amusing how much time and effort is needed to add just one missing character :)

[tconley1428]

Potentially those github outages had some impact on it. Sorry for the trouble, and thanks for the effort.

[brempusz]

@mjameswh, all checks have passed. Could you verify if you can see my CLA signature and merge this PR?

[brempusz]

Guys, is there a way to rerun the checks?