Use github-script action for maintenance_bot job too

Also:
- fix typo in filename
- more explicit binding of argument values

.github/workflows/labels-verifier.yaml

@@ -13,9 +13,13 @@ jobs:
           github.event.pull_request.merged == true &&
           ! contains(join(github.event.pull_request.labels.*.name, ', '), 'kind/') &&
           ! contains(github.event.pull_request.labels.*.name, 'merge')
-        uses: actions/github-script@0.3.0
+        uses: actions/github-script@v3
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           script: |
-            const { issue: { number: issue_number }, repo: { owner, repo }  } = context;
-            github.issues.createComment({ issue_number, owner, repo, body: 'This PR was merged without a "kind/" label, please correct.' })
+            github.issues.createComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: 'This PR was merged without a "kind/" label, please correct.',
+            })

.github/workflows/maintenance_bot.yaml

@@ -19,8 +19,13 @@ jobs:
           ! contains(github.event.pull_request.labels.*.name, 'status/WIP') &&
           ! contains(github.event.pull_request.title, 'WIP') &&
           ! github.event.pull_request.draft
-        run: |
-          curl --request PATCH \
-          --url ${{ github.event.pull_request.issue_url }} \
-          --header 'authorization: token ${{ secrets.GITHUB_TOKEN }}' \
-          --data-raw '{"milestone": '$MILESTONE_NUMBER'}'
+        uses: actions/github-script@v3
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            github.issues.update({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              milestone: ${{ env.MILESTONE_NUMBER }},
+            });