Add release notes for v0.3.16. #3454

Job	Run time
Pre-commit checks / Pre-commit Checks	1m 34s
Check towncrier / Towncrier Checks	29s
Python package / Create Python Package	1m 8s
Unit tests (macos, 3.8)	2m 19s
Unit tests (macos, 3.9)	1m 50s
Unit tests (macos, 3.10)	1m 40s
Unit tests (macos, 3.11)	2m 15s
Unit tests (macos, 3.12)	3m 48s
Unit tests (ubuntu, 3.8)	1m 52s
Unit tests (ubuntu, 3.9)	2m 5s
Unit tests (ubuntu, 3.10)	1m 49s
Unit tests (ubuntu, 3.11)	1m 40s
Unit tests (ubuntu, 3.12)	2m 26s
Unit tests (windows, 3.8)	3m 37s
Unit tests (windows, 3.9)	3m 3s
Unit tests (windows, 3.10)	2m 47s
Unit tests (windows, 3.11)	3m 28s
Unit tests (windows, 3.12)	4m 28s
Unit tests (windows, winstore3.12, false)	4m 37s
Project coverage	37s
Build app (ppb, macos-latest) / Verify App Build	2m 54s
Build app (ppb, ubuntu-22.04) / Verify App Build	3m 37s
Build app (pygame, macos-latest) / Verify App Build	2m 20s
Build app (ppb, windows-latest) / Verify App Build	3m 7s
Build app (pygame, ubuntu-22.04) / Verify App Build	4m 22s
Build app (pygame, windows-latest) / Verify App Build	2m 9s
Build app (pyside2, ubuntu-22.04) / Verify App Build	7m 42s
Build app (pyside2, windows-latest) / Verify App Build	6m 15s
Build app (pyside6, macos-latest) / Verify App Build	3m 37s
Build app (pyside6, ubuntu-22.04) / Verify App Build	9m 11s
Build app (pyside6, windows-latest) / Verify App Build	5m 2s
Build app (toga, macos-latest) / Verify App Build	7m 56s
Build app (toga, ubuntu-22.04) / Verify App Build	13m 15s
Build app (toga, windows-latest) / Verify App Build	7m 13s
	2h 6m 12s

Provide feedback