release: watchexec-supervisor v1.0.3

[github-actions]

This is a release PR for watchexec-supervisor version 1.0.3 (performing a patch bump).

Use squash merge.

Remember to review the crate's changelog!

Upon merging, this will create the tag watchexec-supervisor-v1.0.3.
You will still need to manually publish the cargo crate:

$ git switch main
$ git pull
$ git switch --detach watchexec-supervisor-v1.0.3
$ cargo publish -p watchexec-supervisor

To trigger builds initially: either close and then immediately re-open this PR once, or push to the branch (perhaps with edits to the README.md or CHANGELOG.md!).