Enable excercise execution

[Norbiox]

This PR resolves this issue

What was changed

• Gitpod image version bumped 1.4 -> 1.5
• Added arguments to temporal start command that enables worker deployments
• Arguments added to devcontainer command that starts in codespace and in README.md so that worker deployments works locally too

Why?

Worker deployments didn't exists in Gitpod 1.4. Also the temporal start command lacked arguments needed to enable worker deployments.

Checklist

1. Closes 7

2. How was this tested:

I've runned Codespace and checked in Temporal UI if worker deployments are available. I did it locally too.

3. Any docs updates needed?
   I've already updated README.md

[tomwheeler]

I am going to close this because the 1.5 image was also too old to support the Worker Versioning exercise. As I mentioned in a Slack thread last night, I have published a new image (1.6) that has the latest version. I updated the Codespaces configuration to use that and verified that I could then complete the exercise.

Thank you for the contribution!