⬆ Bump alembic from 1.15.2 to 1.16.5 in /backend (#1847)

Bumps [alembic](https://github.com/sqlalchemy/alembic) from 1.15.2 to 1.16.5.
- [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: 1.16.5
  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 +8,17 @@ resolution-markers = [
 
 [[package]]
 name = "alembic"
-version = "1.15.2"
+version = "1.16.5"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "mako" },
     { name = "sqlalchemy" },
+    { name = "tomli", marker = "python_full_version < '3.11'" },
     { name = "typing-extensions" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/e6/57/e314c31b261d1e8a5a5f1908065b4ff98270a778ce7579bd4254477209a7/alembic-1.15.2.tar.gz", hash = "sha256:1c72391bbdeffccfe317eefba686cb9a3c078005478885413b95c3b26c57a8a7", size = 1925573, upload-time = "2025-03-28T13:52:00.443Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/9a/ca/4dc52902cf3491892d464f5265a81e9dff094692c8a049a3ed6a05fe7ee8/alembic-1.16.5.tar.gz", hash = "sha256:a88bb7f6e513bd4301ecf4c7f2206fe93f9913f9b48dac3b78babde2d6fe765e", size = 1969868, upload-time = "2025-08-27T18:02:05.668Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/41/18/d89a443ed1ab9bcda16264716f809c663866d4ca8de218aa78fd50b38ead/alembic-1.15.2-py3-none-any.whl", hash = "sha256:2e76bd916d547f6900ec4bb5a90aeac1485d2c92536923d0b138c02b126edc53", size = 231911, upload-time = "2025-03-28T13:52:02.218Z" },
+    { url = "https://files.pythonhosted.org/packages/39/4a/4c61d4c84cfd9befb6fa08a702535b27b21fff08c946bc2f6139decbf7f7/alembic-1.16.5-py3-none-any.whl", hash = "sha256:e845dfe090c5ffa7b92593ae6687c5cb1a101e91fa53868497dbd79847f9dbe3", size = 247355, upload-time = "2025-08-27T18:02:07.37Z" },
 ]
 
 [[package]]