maint: further work on dockerizing the flask app.

[emilyashley]

Which problem is this PR solving?

• Touches dockerize the example flask app #72

Short description of the changes

• Get around alpine g++ issue with grpcio wheel build failing by declaring python version and adding build-base to alpine.
• Update opentelemetry dependencies for use together in docker smoke tests.
• Run opentelemetry flask app with poetry and auto-instrumentation and specify different ports for grpc and http test apps.

How to verify that this has the expected result

from smoke-tests, docker-compose build and docker-compose up should get the two test flask apps running ✨

Note: this is for merging into Jamie's docker branch, not main.