Update to Erlang 28.0.2.

[conradwt]

This PR supports the following features:

• update to Erlang 28.0.2

[github-actions]

Docker image tag(s) pushed:

ghcr.io/conradwt/zero-to-graphql-using-elixir:gha-16437157106
ghcr.io/conradwt/zero-to-graphql-using-elixir:pr-272 

Labels added to images:

org.opencontainers.image.created=2025-07-22T07:02:51.436Z
org.opencontainers.image.description=The purpose of this example is to provide details as to how one would go about using GraphQL with the Elixir Language.
org.opencontainers.image.licenses=MIT
org.opencontainers.image.revision=e17f3071c69c5a51354e3d3dfeb0a1dfc2071145
org.opencontainers.image.source=https://github.com/conradwt/zero-to-graphql-using-elixir
org.opencontainers.image.title=zero-to-graphql-using-elixir
org.opencontainers.image.url=https://github.com/conradwt/zero-to-graphql-using-elixir
org.opencontainers.image.version=gha-16437157106