⬆ Bump alembic from 1.13.2 to 1.15.2 in /backend (#1594)

Bumps [alembic](https://github.com/sqlalchemy/alembic) from 1.13.2 to 1.15.2.
- [Release notes](https://github.com/sqlalchemy/alembic/releases)
- [Changelog](https://github.com/sqlalchemy/alembic/blob/main/CHANGES)
- [Commits](https://github.com/sqlalchemy/alembic/commits)

---
updated-dependencies:
- dependency-name: alembic
  dependency-version: 1.15.2
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

backend/uv.lock

@@ -8,16 +8,16 @@ resolution-markers = [
 
 [[package]]
 name = "alembic"
-version = "1.13.2"
+version = "1.15.2"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "mako" },
     { name = "sqlalchemy" },
     { name = "typing-extensions" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/66/e2/efa88e86029cada2da5941ec664d50d9a3b2a91f5066405c6f90e5016c16/alembic-1.13.2.tar.gz", hash = "sha256:1ff0ae32975f4fd96028c39ed9bb3c867fe3af956bd7bb37343b54c9fe7445ef", size = 1206463 }
+sdist = { url = "https://files.pythonhosted.org/packages/e6/57/e314c31b261d1e8a5a5f1908065b4ff98270a778ce7579bd4254477209a7/alembic-1.15.2.tar.gz", hash = "sha256:1c72391bbdeffccfe317eefba686cb9a3c078005478885413b95c3b26c57a8a7", size = 1925573 }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/df/ed/c884465c33c25451e4a5cd4acad154c29e5341e3214e220e7f3478aa4b0d/alembic-1.13.2-py3-none-any.whl", hash = "sha256:6b8733129a6224a9a711e17c99b08462dbf7cc9670ba8f2e2ae9af860ceb1953", size = 232990 },
+    { url = "https://files.pythonhosted.org/packages/41/18/d89a443ed1ab9bcda16264716f809c663866d4ca8de218aa78fd50b38ead/alembic-1.15.2-py3-none-any.whl", hash = "sha256:2e76bd916d547f6900ec4bb5a90aeac1485d2c92536923d0b138c02b126edc53", size = 231911 },
 ]
 
 [[package]]