Buildkite will now generate the docker devcontainer with the vX.Y.Z tag name

[koslambrou]

Buildkite will now generate the docker devcontainer with the vX.Y.Z tag name instead of plutus-starter-devcontainer-v*

Pre-submit checklist:

• Branch
  • Tests are provided (if possible)
  • Commit sequence broadly makes sense
  • Key commits have useful messages
  • Formatting, PNG optimization, etc. are updated
• PR
  • Self-reviewed the diff
  • Useful pull request description
  • Reference the ADR in the PR and reference the PR in the ADR (if revelant)
  • Reviewer requested