Enable 32bit unit test in CI

[falbrechtskirchinger]

Description

The CI image lacks support for -m32 builds, and source lines have to be excluded until that is addressed.

Reproduction steps

n/a

Expected vs. actual results

n/a

Minimal code example

No response

Error messages

No response

Compiler and operating system

n/a

Library version

n/a

Validation

• The bug also occurs if the latest version from the develop branch is used.
• I can successfully compile and run the unit tests.

[nlohmann]

Should work with the latest CI image as used in #3528

[falbrechtskirchinger]

I'll either submit a PR against your new_ci branch or tell you where to git cherry-pick from.

[nlohmann]

I‘m traveling, so a PR would be best.

[nlohmann]

Closed by merging #3532.