Fix Dockerfile

[fixdocker]

Hello, I represent a research group investigating build failures in
Dockerfiles. We executed a Dockerfile in your project and found that
it is not building. We are sending this Pull Request with a suggested
repair. The repair operation is based on the following URL:

• https://stackoverflow.com/a/61564831

Please note that we are using an anonymous GitHub account because of
double-blind restrictions in the submission process of conferences.

[fixdocker]

Hey @capn-freako @jdpatt , can you check this PR?

[jdpatt]

@capn-freako, I'd just vote to delete the Dockerfile. I was using it to verify functionality on Linux. Now with the addition of github actions, I'd suggest using them versus manually creating a linux environment to test.