Handle ImportError in xpress import (#509)

* Handle ImportError in xpress import

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

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: FabianHofmann

linopy/solvers.py

@@ -103,7 +103,7 @@
 
     available_solvers.append("cplex")
 
-with contextlib.suppress(ModuleNotFoundError):
+with contextlib.suppress(ModuleNotFoundError, ImportError):
     import xpress
 
     available_solvers.append("xpress")