chore(gradle): bump org.apache.iceberg:iceberg-bom from 1.8.0 to 1.8.1 (#6672)

Bumps [org.apache.iceberg:iceberg-bom](https://github.com/apache/iceberg) from 1.8.0 to 1.8.1.
- [Release notes](https://github.com/apache/iceberg/releases)
- [Commits](apache/iceberg@apache-iceberg-1.8.0...apache-iceberg-1.8.1)

---
updated-dependencies:
- dependency-name: org.apache.iceberg:iceberg-bom
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

gradle/libs.versions.toml

@@ -39,7 +39,7 @@ gwt = "2.12.1"
 gwtJetty = "9.4.44.v20210927"
 hadoop = "3.4.1"
 hdrhistogram = "2.2.2"
-iceberg = "1.8.0"
+iceberg = "1.8.1"
 immutables = "2.10.1"
 jackson = "2.18.2"
 jakarta-servlet = "5.0.0"