Bump actions/setup-python from 4 to 6 (#7923)

Bumps [actions/setup-python](https://github.com/actions/setup-python) from 4 to 6.
- [Release notes](https://github.com/actions/setup-python/releases)
- [Commits](actions/setup-python@v4...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>

Author: dependabot[bot]

.github/workflows/assemble_changelog.yml

@@ -17,7 +17,7 @@ jobs:
           ref: ${{github.head_ref}}
 
       - name: setup python
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v6
         with:
           python-version: '3.7.7'
 

.github/workflows/rename_changelog_file.yml

@@ -18,7 +18,7 @@ jobs:
           ref: ${{github.head_ref}}
 
       - name: setup python
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v6
         with:
           python-version: '3.7.7'