set the git user email when updating deployments file

[tjenkinson]

This PR will...

Set the git user email when updating deployments file

Why is this Pull Request needed?

Without this it tries to come up with a sensible default but recently this failed in https://github.com/video-dev/hls.js/actions/runs/4217828503/jobs/7321920416 with

Author identity unknown

*** Please tell me who you are.

Run

  git config --global user.email "you@example.com"
  git config --global user.name "Your Name"

to set your account's default identity.
Omit --global to set the identity only in this repository.

fatal: unable to auto-detect email address (got 'runner@fv-az581-156.(none)')
Error: Process completed with exit code 128.

I've set it to the email of the CI user it's actually using.