[EPIC] Release Gravitino 1.3.1

### Describe the proposal

This issue tracks all the work to release Gravitino 1.3.1. Release manager: @bharos

### Task list

**Pre-release**
- [ ] Code freeze on `branch-1.3` — Friday 4 September
- [ ] LICENSE/NOTICE audit: diff bundled jars against each of the four distributions (main, iceberg-rest-server, lance-rest-server, trino-connector) and verify NOTICE content is propagated
- [ ] Dry run: `./dev/release/do-release.sh -n -b branch-1.3`

**RC1**
- [ ] Cut rc1: `./dev/release/do-release.sh -b branch-1.3 -r 1`
- [ ] Verify artifacts in https://dist.apache.org/repos/dist/dev/gravitino/v1.3.1-rc1/
- [ ] Verify PyPI staging: https://pypi.org/project/apache-gravitino/1.3.1rc1/
- [ ] Verify Maven staging: https://repository.apache.org/\#stagingRepositories
- [ ] Verify Docker images:
- https://hub.docker.com/r/apache/gravitino/tags
- https://hub.docker.com/r/apache/gravitino-iceberg-rest/tags
- https://hub.docker.com/r/apache/gravitino-lance-rest/tags
- https://hub.docker.com/r/apache/gravitino-mcp-server/tags
- https://hub.docker.com/r/apache/gravitino-playground/tags
- [ ] Send `[VOTE]` to dev@gravitino.apache.org (≥72h, 3 binding +1 required)

**If vote fails → fix issues and repeat from RC with incremented RC number**

**Finalize** _(PMC assistance needed for starred items)_
- [ ] ⭐ Promote Maven staging → release (Nexus)
- [ ] ⭐ `svn mv` dist/dev/gravitino/v1.3.1-rcN → dist/release/gravitino/1.3.1/
- [ ] ⭐ Publish final PyPI package: https://pypi.org/project/apache-gravitino/1.3.1/
- [ ] Send `[RESULT][VOTE]` to dev@gravitino.apache.org
- [ ] Send `[ANNOUNCE]` to dev@gravitino.apache.org and announce@apache.org
- [ ] Add download link and release notes to website