fix(deps): update flatlaf to v3.5.4

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
com.formdev:flatlaf-extras	3.5.3 -> 3.5.4
com.formdev:flatlaf	3.5.3 -> 3.5.4

---

Release Notes

JFormDesigner/FlatLaf (com.formdev:flatlaf-extras)

v3.5.4

Compare Source

Fixed bugs

• HTML: Fixed NPE when using HTML text on a component with null font. (issue
  #​930; PR #​931; regression in 3.5)
• Linux: Fixed NPE when using FlatLaf window decorations and switching theme.
  (issue #​933; regression in 3.5.3)

---

Configuration

📅 Schedule: Branch creation - "before 9am" in timezone UTC, Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about these updates again.

---

• If you want to rebase/retry this PR, check this box

---

This PR was generated by Mend Renovate. View the repository job log.