Add changelog for 3.28.2

Signed-off-by: tobiasKaminsky <tobias@kaminsky.me>

CHANGELOG.md

@@ -1,3 +1,12 @@
+## 3.28.2 (April 4th, 2024)
+
+- Bugfixes
+
+
+Minimum: NC 16 Server, Android 7.0 Nougat
+
+For a full list, please see https://github.com/nextcloud/android/milestone/90
+
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