ci(deps): bump actions/setup-python from 5 to 6 (XRPLF#361)

Bumps [actions/setup-python](https://github.com/actions/setup-python) from 5 to 6.
- [Release notes](https://github.com/actions/setup-python/releases)
- [Commits](actions/setup-python@v5...v6)

---
updated-dependencies:
- dependency-name: actions/setup-python
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Mayukha Vadari <mvadari@ripple.com>

Author: dependabot[bot]

.github/workflows/deploy.yml

@@ -23,7 +23,7 @@ jobs:
         uses: actions/checkout@v5
 
       - name: Setup Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: "3.11"
 

.github/workflows/validate-xls.yml

@@ -16,7 +16,7 @@ jobs:
         uses: actions/checkout@v5
 
       - name: Setup Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: "3.11"