Update pyproject.toml

pyproject.toml

@@ -53,7 +53,7 @@ parsl = ["parsl[monitoring]>=2024.5.27; platform_system!='Windows'"]
 phonons = ["phonopy>=2.20.0", "seekpath>=2.1.0"]
 prefect = ["prefect[dask]>=2.19.0,<3.0", "dask-jobqueue>=0.8.2"]
 redun = ["redun>=0.16.2"]
-sella = ["sella @ git+https://github.com/zadorlab/sella.git@refs/pull/46/merge"]
+sella = ["sella @ git+https://github.com/zadorlab/sella.git@refs/pull/46/head"]
 tblite = ["tblite>=0.3.0; platform_system=='Linux'"]
 dev = ["pytest>=7.4.0", "pytest-cov>=3.0.0", "ruff>=0.0.285"]
 docs = [