chore(deps): update urfave/cli/v3 to v3.9.0 (#37863)

Updates `github.com/urfave/cli/v3` to
[v3.9.0](https://github.com/urfave/cli/releases/tag/v3.9.0) and removes
the renovate pin now that
[urfave/cli#2319](https://github.com/urfave/cli/pull/2319) (the `-c`
help flag parsing fix) is merged.

v3.9.0 prepends the default command name to the root command's args,
which broke the old `Root().Args()` check in `isValidDefaultSubCommand`.
It now uses the command's own `Args()`.

Behavior change: `./gitea web <extra-positional-arg>` now errors with
`unknown command` instead of starting the web server and ignoring the
trailing arg. `web` takes no positional args, so this is stricter (and
arguably more correct) input handling. The intended `./gitea bad-cmd`
rejection is unchanged.

---
This PR was written with the help of Claude Opus 4.7

---------

Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>
Co-authored-by: Nicolas <bircni@icloud.com>

renovate.json5

@@ -39,10 +39,6 @@
       "matchPackageNames": ["tailwindcss"],
       "allowedVersions": "^3", // need to migrate
     },
-    {
-      "matchPackageNames": ["github.com/urfave/cli/v3"],
-      "allowedVersions": "<3.6.2", // v3.6.2 breaks -c flag parsing in help commands
-    },
     {
       "matchPackageNames": ["github.com/Azure/azure-sdk-for-go/sdk/azcore"],
       "allowedVersions": "<1.21.0", // v1.21.0+ uses API version unsupported by Azurite in CI