pyproject.toml: add highspy as optional dependency

Author: rschwarz

pyproject.toml

@@ -37,6 +37,7 @@ dependencies = ["cffi==1.15.*"]
 [project.optional-dependencies]
 numpy = ["numpy==1.24.*; python_version >= '3.8'", "numpy==1.21.6; python_version == '3.7'"]
 gurobi = ["gurobipy>=8"]
+highs = ["highspy>=1.5"]
 test = ["pytest==7.2.0", "networkx==2.8.8; python_version >= '3.8'", "networkx==2.6.3; python_version == '3.7'", "matplotlib==3.6.2; python_version >= '3.8'", "matplotlib==3.5.3; python_version == '3.7'"]
 
 [project.urls]
@@ -50,4 +51,4 @@ packages = ["mip"]
 "mip.libraries" = ["*.so", "*.dylib", "*.dll"]
 
 [tool.setuptools_scm]
-write_to = "mip/_version.py"
+write_to = "mip/_version.py"