Bump ray from 1.1.0 to 2.8.1 in /examples/spreadsheet

Bumps [ray](https://github.com/ray-project/ray) from 1.1.0 to 2.8.1.
- [Release notes](https://github.com/ray-project/ray/releases)
- [Commits](ray-project/ray@ray-1.1.0...ray-2.8.1)

---
updated-dependencies:
- dependency-name: ray
  dependency-type: direct:production
...

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

Author: dependabot[bot]

examples/spreadsheet/requirements.txt

@@ -1,3 +1,3 @@
-ray==1.1.0
+ray==2.8.1
 git+https://github.com/modin-project/modin
 git+https://github.com/modin-project/modin-spreadsheet.git@49ffd89f683f54c311867d602c55443fb11bf2a5