Fix installation of alembic.ini

As hinted in https://github.com/jupyterhub/jupyterhub/issues/4593,
build-depend on python3-setuptools-scm rather than adding alembic.ini
incorrectly to `data_files` (it should have been a tuple of the path to
install to and a list of files; but this approach is easier).

Closes: #1100077

debian/changelog

+jupyterhub (5.2.1+ds1-2) UNRELEASED; urgency=medium
+
+  * Build-depend on python3-setuptools-scm rather than adding alembic.ini
+    incorrectly to data_files (closes: #1100077).
+
+ -- Colin Watson <cjwatson@debian.org>  Sun, 16 Mar 2025 16:33:28 +0000
+
 jupyterhub (5.2.1+ds1-1) unstable; urgency=medium
 
   * New upstream release.

debian/control

@@ -27,6 +27,7 @@ Build-Depends:
  python3-requests,
  python3-requests-mock,
  python3-setuptools,
+ python3-setuptools-scm,
  python3-tornado,
  python3-traitlets,
 # Testsuite: autopkgtest-pkg-pybuild

debian/patches/0004-Include-alembic.ini.patch

-From: Roland Mas <lolando@debian.org>
-Date: Sun, 29 Sep 2024 16:17:01 +0200
-Subject: Include alembic.ini
-
----
- setup.py | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
-diff --git a/setup.py b/setup.py
-index 736f958..439eb92 100755
---- a/setup.py
-+++ b/setup.py
-@@ -270,7 +270,7 @@ cmdclass = {
- def main():
-     setup(
-         cmdclass=cmdclass,
--        data_files=get_data_files(),
-+        data_files=["jupyterhub/alembic.ini"] + get_data_files(),
-     )
- 
- 

debian/patches/series

 0001-Add-empty-config-file.patch
 0002-Use-configurable-http-proxy-instead-of-Traefik.patch
 0003-Do-not-use-npm-even-if-available-during-build.patch
-0004-Include-alembic.ini.patch