build(deps): bump dawidd6/action-send-mail from 3 to 4

Bumps [dawidd6/action-send-mail](https://github.com/dawidd6/action-send-mail) from 3 to 4.
- [Release notes](https://github.com/dawidd6/action-send-mail/releases)
- [Commits](dawidd6/action-send-mail@v3...v4)

---
updated-dependencies:
- dependency-name: dawidd6/action-send-mail
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/email-notification.yml

@@ -25,7 +25,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Send mail
-        uses: dawidd6/action-send-mail@v3
+        uses: dawidd6/action-send-mail@v4
         with:
           subject: ${{ inputs.subject }}
           body: ${{ inputs.body }}