bump the build metadata (#10592)

* require at least `setuptools=77.0.3`

which is necessary because we switched to the new license string (SPDX,
from PEP 639)

* require `setuptools-scm>=8` at the same time

* specify the actual release that officially added support

Author: keewis

pyproject.toml

@@ -98,7 +98,7 @@ dask = "xarray.namedarray.daskmanager:DaskManager"
 
 [build-system]
 build-backend = "setuptools.build_meta"
-requires = ["setuptools>=42", "setuptools-scm>=7"]
+requires = ["setuptools>=77.0.3", "setuptools-scm>=8"]
 
 [tool.setuptools.packages.find]
 include = ["xarray*"]