Resolve "retrieving packages crashes with "Character set 'utf8' unsupported""

What does this MR do?

This switches from the mysql Pythone connector package to the MariaDB packages.

The "edge" version of Alpine was required to successfully build the MariaDB Python package. The change probably results in a larger image, as it requires to install a C compiler and some libraries in the Dockerfile. This is acceptable I think, as image size is not an issue at the moment.

Changes to public APIs

Author's checklist (required)

• Intermediate commits compile (use git rebase -i main if not)
• Newly added code has a style consistent with the rest of the repository
• Newly added code is documented (guidelines)

Related issues

Closes #8 (closed)