chore(renovate): update python packages even when change is only needed in uv.lock

Since some time around April, renovate started to update only
packages, where `pyproject.toml` update was needed (constraints
update).

I have not found documentation about this change, only a github discussion[^1].

Meaning of rangeStrategy=update-lockfile[^2] option:

> Update the lock file when in-range updates are available, otherwise
> replace for updates out of range.

And replace:

> Replace the range with a newer one if the new version falls outside
> it, and update nothing otherwise

[^1]: renovatebot/renovate#36286
[^2]: https://docs.renovatebot.com/configuration-options/#rangestrategy

Author: vlaci

renovate.json

@@ -24,6 +24,9 @@
     "enabled": true,
     "description": "opt-in support for nix https://docs.renovatebot.com/modules/manager/nix/#enabling"
   },
+  "pep621": {
+    "rangeStrategy": "update-lockfile"
+  },
   "pre-commit": {
     "enabled": true,
     "description": "opt-in support for pre-commit  https://docs.renovatebot.com/modules/manager/nix/#enabling"