Handle ImportError in xpress import

[FabianHofmann]

Also catch ImportError for xpress import. This should resolve rarely occuring compat problem with numpy packages

Checklist

• Code changes are sufficiently documented; i.e. new functions contain docstrings and further explanations may be given in doc.
• Unit tests for new features were added (if applicable).
• A note for the release notes doc/release_notes.rst of the upcoming release is included.
• I consent to the release of this PR's code under the MIT license.