Add changelog for 3.3.0-RC4

Author: Kordyjan

changelogs/3.3.0-RC4.md

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+# Backported fixes
+
+- Fix HK quoted pattern type variables [#16907](https//github.com/lampepfl/dotty/pull/16907)
+- Fix caching issue caused by incorrect isProvisional check [#16989](https://github.com/lampepfl/dotty/pull/16989)
+- Fix race condition in new LazyVals [#16975](https://github.com/lampepfl/dotty/pull/16975)
+- Fix "-Wunused: False positive on parameterless enum member" [#16927](https://github.com/lampepfl/dotty/pull/16927)
+- Register usage of symbols in non-inferred type trees in CheckUnused [#16939](https://github.com/lampepfl/dotty/pull/16939)
+- Traverse annotations instead of just registering in -W [#16956](https://github.com/lampepfl/dotty/pull/16956)
+- Ignore parameter of accessors in -Wunused [#16957](https://github.com/lampepfl/dotty/pull/16957)
+- Improve override detection in CheckUnused [#16965](https://github.com/lampepfl/dotty/pull/16965)
+- WUnused: Fix unused warning in synthetic symbols [#17020](https://github.com/lampepfl/dotty/pull/17020)
+- Fix WUnused with idents in derived code [#17095](https//github.com/lampepfl/dotty/pull/17095)
+- WUnused: Fix for symbols with synthetic names and unused transparent inlines [#17061](https//github.com/lampepfl/dotty/pull/17061)
+- Skip extension method params in WUnused [#17178](https//github.com/lampepfl/dotty/pull/17178)
+- Fix wunused false positive when deriving alias type [#17157](https//github.com/lampepfl/dotty/pull/17157)
+- Fix WUnused for accessible symbols that are renamed [#17177](https//github.com/lampepfl/dotty/pull/17177)
+- Fix WUnused false positive in for [#17176](https//github.com/lampepfl/dotty/pull/17176)
+- Make CheckUnused run both after Typer and Inlining [#17206](https//github.com/lampepfl/dotty/pull/17206)
+- Disable WUnused for params of non-private defs [#17223](https//github.com/lampepfl/dotty/pull/17223)
+
+# Contributors
+
+Thank you to all the contributors who made this release possible 🎉
+
+According to `git shortlog -sn --no-merges 3.3.0-RC3..3.3.0-RC4` these are:
+
+```
+    41 Szymon Rodziewicz
+     4 Paul Coral
+     3 Paweł Marks
+     1 Guillaume Martres
+     1 Kacper Korban
+     1 Nicolas Stucki
+
+```