🐛 Fix broken manylinux wheels

[burgholzer]

Description

Due to the way Linux wheels are built by cibuildwheel (in a manylinux docker container), environment varaiables are not passed down to the container. As a result the CI environment variable is not defined in the docker container, which is used to flip on the DEPLOY CMake setting automatically.
This has lead to manylinux wheels being built with -march=native that might produce errors like

Illegal instruction (core dumped)

when trying to import the respective packages.

This PR fixes this by making sure that DEPLOY="ON" within cibuildwheel.

Fixes #288

Checklist:

• The pull request only contains commits that are related to it.
• I have added appropriate tests and documentation.
• I have made sure that all CI jobs on GitHub pass.
• The pull request introduces no new warnings and follows the project's style guidelines.