Drop python3.8 support (SciTools#5269)

* Drop python3.8 support

* whatsnew

Author: rcomer

.github/workflows/ci-tests.yml

@@ -48,9 +48,6 @@ jobs:
           - os: "ubuntu-latest"
             python-version: "3.9"
             session: "tests"
-          - os: "ubuntu-latest"
-            python-version: "3.8"
-            session: "tests"
 
     env:
       IRIS_TEST_DATA_VERSION: "2.19"

.github/workflows/ci-wheels.yml

@@ -52,7 +52,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11"]
+        python-version: ["3.9", "3.10", "3.11"]
         session: ["wheel"]
     env:
       ENV_NAME: "ci-wheels"

docs/src/whatsnew/latest.rst

@@ -30,29 +30,6 @@ This document explains the changes made to Iris for this release
 ✨ Features
 ===========
 
-#. `@bsherratt`_ added support for plugins - see the corresponding
-   :ref:`documentation page<community_plugins>` for further information.
-   (:pull:`5144`)
-
-#. `@rcomer`_ enabled lazy evaluation of :obj:`~iris.analysis.RMS` calcuations
-   with weights. (:pull:`5017`)
-
-#. `@schlunma`_ allowed the usage of cubes, coordinates, cell measures, or
-   ancillary variables as weights for cube aggregations
-   (:meth:`iris.cube.Cube.collapsed`, :meth:`iris.cube.Cube.aggregated_by`, and
-   :meth:`iris.cube.Cube.rolling_window`). This automatically adapts cube units
-   if necessary. (:pull:`5084`)
-
-#. `@lbdreyer`_ and `@trexfeathers`_ (reviewer)  added :func:`iris.plot.hist` 
-   and :func:`iris.quickplot.hist`. (:pull:`5189`)
-
-#. `@tinyendian`_ edited :func:`~iris.analysis.cartography.rotate_winds` to
-   enable lazy computation of rotated wind vector components (:issue:`4934`,
-   :pull:`4972`)
-
-#. `@ESadek-MO`_ updated to the latest CF Standard Names Table v80
-   (07 February 2023). (:pull:`5244`)
-
 #. `@pp-mo`_ and  `@lbdreyer`_ supported delayed saving of lazy data, when writing to
    the netCDF file format.  See : :ref:`delayed netCDF saves <delayed_netcdf_save>`.
    Also with significant input from `@fnattino`_.
@@ -87,7 +64,10 @@ This document explains the changes made to Iris for this release
 ===============
 
 #. `@rcomer`_ and `@bjlittle`_ (reviewer) added testing support for python
-   3.11. (:pull:`5226`) 
+   3.11. (:pull:`5226`)
+
+#. `@rcomer`_ dropped support for python 3.8, in accordance with the NEP29_
+   recommendations (:pull:`5226`) 
 
 
 📚 Documentation
@@ -127,7 +107,6 @@ This document explains the changes made to Iris for this release
     core dev names are automatically included by the common_links.inc:
 
 .. _@fnattino: https://github.com/fnattino
-.. _@tinyendian: https://github.com/tinyendian
 
 
 .. comment
@@ -137,4 +116,5 @@ This document explains the changes made to Iris for this release
 .. _sphinx-design: https://github.com/executablebooks/sphinx-design
 .. _check-manifest: https://github.com/mgedmin/check-manifest
 .. _PEP-0621: https://peps.python.org/pep-0621/
-.. _pypa/build: https://pypa-build.readthedocs.io/en/stable/
+.. _pypa/build: https://pypa-build.readthedocs.io/en/stable/
+.. _NEP29: https://numpy.org/neps/nep-0029-deprecation_policy.html

lib/iris/tests/test_coding_standards.py

@@ -72,7 +72,7 @@ def test_python_versions():
     updated, insisting that versions are updated EVERYWHERE in-sync.
     """
     latest_supported = "3.11"
-    all_supported = ["3.8", "3.9", "3.10", latest_supported]
+    all_supported = ["3.9", "3.10", latest_supported]
 
     root_dir = Path(__file__).parents[3]
     workflows_dir = root_dir / ".github" / "workflows"

noxfile.py

@@ -16,7 +16,7 @@
 nox.options.reuse_existing_virtualenvs = True
 
 #: Python versions we can run sessions under
-_PY_VERSIONS_ALL = ["3.8", "3.9", "3.10", "3.11"]
+_PY_VERSIONS_ALL = ["3.9", "3.10", "3.11"]
 _PY_VERSION_LATEST = _PY_VERSIONS_ALL[-1]
 
 #: One specific python version for docs builds

pyproject.toml

@@ -22,7 +22,6 @@ classifiers = [
     "Operating System :: Unix",
     "Programming Language :: Python",
     "Programming Language :: Python :: 3 :: Only",
-    "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
@@ -51,7 +50,7 @@ keywords = [
 ]
 license = {text = "LGPL-3.0-or-later"}
 name = "scitools-iris"
-requires-python = ">=3.8"
+requires-python = ">=3.9"
 
 [project.urls]
 Code = "https://github.com/SciTools/iris"
@@ -78,7 +77,7 @@ version_scheme = "release-branch-semver"
 
 [tool.black]
 line-length = 79
-target-version = ['py38']
+target-version = ['py39']
 include = '\.pyi?$'
 extend-exclude = '''
 (