Update Dockerfile

[PeterDaveHello]

Description

Update Dockerfile

Motivation and Context

Make the Docker image better!

Size before and after this PR: 15.4MB vs 14.9MB!

The --no-cache & COPY changes are folloing the Dockerfile best practices, see more details here:
https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#add-or-copy

How Has This Been Tested?

docker build -t temp .

Checklist

• No code changes (src/ is unmodified: changes to documentation, CI, metadata, etc.)
• Dependency changes (any modification to dependencies in package.json)
• Bug fixes (non-breaking change which fixes an issue)
• Improvements (misc. changes to existing features)
• Features (non-breaking change which adds functionality)

My changes...

• are breaking changes to a public API (config options, System API, major UI change, etc).
• are breaking changes to a private API (Redux, component props, utility functions, etc.).
• are breaking changes to a developer API (npm script behavior changes, new dev system dependencies, etc).
• are not breaking changes.

Documentation

• My changes do not require a change to the project documentation.
• My changes require a change to the project documentation.
• If yes to above: I have updated the documentation accordingly.

Automated tests

• My changes can not or do not need to be tested.
• My changes can and should be tested by unit and/or integration tests.
• If yes to above: I have added tests to cover my changes.
• If yes to above: I have taken care to cover edge cases in my tests.
• All new and existing tests passed.

[shockey]

thanks @PeterDaveHello!