Fix flaky SCIP time limit test (fixes #577)

[FabianHofmann]

Closes #577.

Changes proposed in this Pull Request

• Increased the SCIP time limit in test_solver_time_limit_options from 1 second to 10 seconds.
• The test only verifies that the solver accepts the time limit parameter, not that the limit is actually hit. On slow CI runners, the 1-second limit could occasionally be reached during file I/O and model parsing overhead, causing flaky failures.
• A 10-second limit still validates that the parameter works while eliminating the race condition.

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.