Fix announcement cell heading

[andreslucena]

🎩 What? Why?

Reviewing v0.24 with @carolromero we've noticed that there are some new big titles in announcement. The font is too big, so this PR fixes that.

📌 Related Issues

• Related to Allow multiple lines in announcement block #7341

Testing

Open any announcement.

📋 Checklist

🚨 Please review the guidelines for contributing to this repository.

• ❓ CONSIDER adding a unit test if your PR resolves an issue.
• ✔️ DO check open PR's to avoid duplicates.
• ✔️ DO keep pull requests small so they can be easily reviewed.
• ✔️ DO build locally before pushing.
• ✔️ DO make sure tests pass.
• ✔️ DO make sure any new changes are documented in docs/.
• ✔️ DO add and modify seeds if necessary.
• ✔️ DO add CHANGELOG upgrade notes if required.
• ✔️ DO add to GraphQL API if there are new public fields.
• ✔️ DO add link to MetaDecidim if it's a new feature.
• ❌AVOID breaking the continuous integration build.
• ❌AVOID making significant changes to the overall architecture.

📷 Screenshots

Before

After

♥️ Thank you!