Make trivial formatting changes to "Check Certificates" workflow

No functional change, and neither is necessarily superior, but this is the formatting style either defined in the
"template", or by the repository's Prettier formatting configuration preferences, so it must be brought into compliance
here as well.

.github/workflows/check-certificates.yml

@@ -4,13 +4,13 @@ name: Check Certificates
 on:
   push:
     paths:
-      - ".github/workflows/check-certificates.ya?ml"
+      - '.github/workflows/check-certificates.ya?ml'
   pull_request:
     paths:
-      - ".github/workflows/check-certificates.ya?ml"
+      - '.github/workflows/check-certificates.ya?ml'
   schedule:
     # Run every 10 hours.
-    - cron: "0 */10 * * *"
+    - cron: '0 */10 * * *'
   workflow_dispatch:
   repository_dispatch:
 
@@ -25,9 +25,7 @@ jobs:
     if: >
       (github.event_name != 'pull_request' && github.repository == 'arduino/arduino-ide') ||
       (github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == 'arduino/arduino-ide')
-    
     runs-on: ubuntu-latest
-
     strategy:
       fail-fast: false
 
@@ -68,7 +66,6 @@ jobs:
 
       - name: Slack notification of certificate verification failure
         if: failure()
-        uses: rtCamp/action-slack-notify@v2.1.0
         env:
           SLACK_WEBHOOK: ${{ secrets.TEAM_TOOLING_CHANNEL_SLACK_WEBHOOK }}
           SLACK_MESSAGE: |
@@ -77,6 +74,7 @@ jobs:
             :warning::warning::warning::warning:
           SLACK_COLOR: danger
           MSG_MINIMAL: true
+        uses: rtCamp/action-slack-notify@v2.1.0
 
       - name: Get days remaining before certificate expiration date
         env:
@@ -122,7 +120,6 @@ jobs:
       - name: Slack notification of pending certificate expiration
         # Don't send spurious expiration notification if verification fails.
         if: failure() && steps.check-expiration.outcome == 'failure'
-        uses: rtCamp/action-slack-notify@v2.1.0
         env:
           SLACK_WEBHOOK: ${{ secrets.TEAM_TOOLING_CHANNEL_SLACK_WEBHOOK }}
           SLACK_MESSAGE: |
@@ -131,3 +128,4 @@ jobs:
             :warning::warning::warning::warning:
           SLACK_COLOR: danger
           MSG_MINIMAL: true
+        uses: rtCamp/action-slack-notify@v2.1.0