Bump actions/github-script from 7 to 8 (#36157)

Bumps [actions/github-script](https://github.com/actions/github-script) from 7 to 8.
- [Release notes](https://github.com/actions/github-script/releases)
- [Commits](actions/github-script@v7...v8)

---
updated-dependencies:
- dependency-name: actions/github-script
  dependency-version: '8'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/assign_milestone.yml

@@ -35,7 +35,7 @@ jobs:
         with:
           fetch-depth: 2
 
-      - uses: actions/github-script@v7
+      - uses: actions/github-script@v8
         with:
           script: |
             const fs = require('fs')

.github/workflows/self-assign.yml

@@ -25,7 +25,7 @@ jobs:
     if: ${{ !github.event.issue.pull_request }}
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/github-script@v7
+    - uses: actions/github-script@v8
       with:
         script: |
           const body = context.payload.comment.body.replace( /\r\n/g, " " ).replace( /\n/g, " " ).split(' ');