Update module golang.org/x/oauth2 to v0.29.0 (forgejo) (#7475)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [golang.org/x/oauth2](https://pkg.go.dev/golang.org/x/oauth2) | require | minor | [`v0.28.0` -> `v0.29.0`](https://cs.opensource.google/go/x/oauth2/+/refs/tags/v0.28.0...refs/tags/v0.29.0) |

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Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7475
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Renovate Bot <forgejo-renovate-action@forgejo.org>
Co-committed-by: Renovate Bot <forgejo-renovate-action@forgejo.org>