Bump osgeo/gdal in /index

Bumps [osgeo/gdal](https://github.com/OSGeo/gdal) from ubuntu-small-3.10.3 to ubuntu-small-3.12.0.
- [Release notes](https://github.com/OSGeo/gdal/releases)
- [Changelog](https://github.com/OSGeo/gdal/blob/master/NEWS.md)
- [Commits](https://github.com/OSGeo/gdal/commits)

---
updated-dependencies:
- dependency-name: osgeo/gdal
  dependency-version: ubuntu-small-3.12.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

index/Dockerfile

@@ -1,7 +1,7 @@
 # syntax=docker/dockerfile:1
 FROM ghcr.io/astral-sh/uv:0.9.10@sha256:29bd45092ea8902c0bbb7f0a338f0494a382b1f4b18355df5be270ade679ff1d AS uv
 
-FROM ghcr.io/osgeo/gdal:ubuntu-small-3.10.3@sha256:dab45abca3ca83695d442018692f4f8a0f41955871c57e6101d7f89a92375caa AS base
+FROM ghcr.io/osgeo/gdal:ubuntu-small-3.12.0@sha256:9c3f7d8caf2a36762385d4868e198660a90b0c896f86b01fcab26953770b794e AS base
 
 FROM base AS builder