Use ENTRYPOINT instead of CMD in Dockerfile

[gauravgahlot]

What this PR does / why we need it:

Closes #239

Special notes for your reviewer:

If applicable:

• this PR has an associated PR with documentation in akri-docs
• this PR contains unit tests
• added code adheres to standard Rust formatting (cargo fmt)
• code builds properly (cargo build)
• code is free of common mistakes (cargo clippy)
• all Akri tests succeed (cargo test)
• inline documentation builds (cargo doc)
• all commits pass the DCO bot check by being signed off -- see the failing DCO check for instructions on how to retroactively sign commits

[gauravgahlot]

/version patch

[bfjelds]

change looks good, it would be nice to have the tests run on it though.

[diconico07]

change looks good, it would be nice to have the tests run on it though.

About tests runs, I noticed the GitHub action to bump version doesn't re-trigger all tests, but you can still look at the test results of previous commit (with obviously the version test that fails) for that, I didn't find the root cause of tests not running, so that's my workaround