build(deps-dev): bump highspy from 1.13.1 to 1.15.0 (#809)

Bumps [highspy](https://github.com/ERGO-Code/HiGHS) from 1.13.1 to 1.15.0.
- [Release notes](https://github.com/ERGO-Code/HiGHS/releases)
- [Commits](ERGO-Code/HiGHS@v1.13.1...v1.15.0)

---
updated-dependencies:
- dependency-name: highspy
  dependency-version: 1.15.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

pyproject.toml

@@ -85,7 +85,7 @@ dev = [
 # Perf-relevant deps pinned exactly so run-to-run deltas reflect linopy
 # changes, not dependency bumps.
 benchmarks = [
-    "highspy==1.13.1",
+    "highspy==1.15.0",
     "netcdf4==1.7.4",
     "numpy==2.4.6",
     "scipy==1.17.1",