🎨Only use setuptools-scm-git-archive under < py37

`setuptools-scm` support Git archives natively starting v7 but it only
supports Python 3.7 or higher. This patch makes up a set of
conditional build dependencies that add `setuptools-scm-git-archive`
only below Python 3.7 and in combination with an older version of
`setuptools-scm`. Close #515

.git_archival.txt

@@ -1 +1,4 @@
+node: $Format:%H$
+node-date: $Format:%cI$
+describe-name: $Format:%(describe:tags=true)$
 ref-names: $Format:%D$

pyproject.toml

@@ -6,8 +6,12 @@ requires = [
     "setuptools>=34.4",
 
     # Plugins
-    "setuptools_scm[toml]>=3.5",
-    "setuptools_scm_git_archive>=1.1",
+    "setuptools-scm >= 3.5; python_version >= '3.7'",
+    #  ^    supports git archives through a plugin
+    #  |                                        |
+    # supports git archives natively            V
+    "setuptools-scm[toml] >= 3.5; python_version < '3.7'",
+    "setuptools-scm-git-archive >= 1.1; python_version < '3.7'",
 ]
 build-backend = "setuptools.build_meta"
 

requirements/dist-build-constraints.in

@@ -6,7 +6,6 @@ setuptools >= 34.4
 
 # Plugins
 setuptools_scm[toml] >= 3.5
-setuptools_scm_git_archive >= 1.1
 
 # Dynamic (coming from setuptools' PEP 517 build backend)
 wheel

setup.cfg

@@ -65,7 +65,6 @@ include_package_data = True
 # These are required during `setup.py` run:
 setup_requires =
   setuptools_scm>=1.15.0
-  setuptools_scm_git_archive>=1.0
 
 # These are required in actual runtime:
 install_requires =