add pyproject.toml (pydata#4897)

* add a initial pyproject.toml file

* reformat the toml file

* use setuptools_scm_git_archive to support git archives

* add entries for whats-new.rst

* remove setup_requires

* require setuptools >= 42 since that's required for using pyproject.toml

* add a fallback version

.git_archival.txt

@@ -0,0 +1 @@
+ref-names: $Format:%D$

.gitattributes

@@ -1,2 +1,4 @@
 # reduce the number of merge conflicts
 doc/whats-new.rst merge=union
+# allow installing from git archives
+.git_archival.txt  export-subst

doc/whats-new.rst

@@ -34,6 +34,9 @@ Breaking changes
 
   (:issue:`4688`, :pull:`4720`)
   By `Justus Magin <https://github.com/keewis>`_.
+- use ``pyproject.toml`` instead of the ``setup_requires`` option for
+  ``setuptools`` (:pull:`4897`).
+  By `Justus Magin <https://github.com/keewis>`_.
 - As a result of :pull:`4684` the default units encoding for
   datetime-like values (``np.datetime64[ns]`` or ``cftime.datetime``) will now
   always be set such that ``int64`` values can be used.  In the past, no units
@@ -86,6 +89,8 @@ New Features
 - :py:meth:`DataArray.swap_dims` & :py:meth:`Dataset.swap_dims` now accept dims
   in the form of kwargs as well as a dict, like most similar methods.
   By `Maximilian Roos <https://github.com/max-sixty>`_.
+- Allow installing from git archives (:pull:`4897`).
+  By `Justus Magin <https://github.com/keewis>`_.
 
 - :py:func:`open_dataset` and :py:func:`open_mfdataset` now accept ``fsspec`` URLs
   (including globs for the latter) for ``engine="zarr"``, and so allow reading from

pyproject.toml

@@ -0,0 +1,11 @@
+[build-system]
+requires = [
+    "setuptools>=42",
+    "wheel",
+    "setuptools_scm[toml]>=3.4",
+    "setuptools_scm_git_archive",
+]
+build-backend = "setuptools.build_meta"
+
+[tool.setuptools_scm]
+fallback_version = "999"

setup.cfg

@@ -77,10 +77,6 @@ install_requires =
     numpy >= 1.15
     pandas >= 0.25
     setuptools >= 40.4  # For pkg_resources
-setup_requires =
-    setuptools >= 40.4
-    setuptools_scm
-
 
 [options.extras_require]
 io =