Migrate plugin_platform_interface to v2 stable, null-safe (#3543)

packages/plugin_platform_interface/CHANGELOG.md

diff --git a/packages/plugin_platform_interface/CHANGELOG.md b/packages/plugin_platform_interface/CHANGELOG.md
index 96533f0..cea8f2a 100644
--- a/packages/plugin_platform_interface/CHANGELOG.md
+++ b/packages/plugin_platform_interface/CHANGELOG.md
@@ -1,12 +1,4 @@
-## 1.1.0-nullsafety.2
-
-* Use Mockito null safe.
-
-## 1.1.0-nullsafety.1
-
-* Bump Dart SDK to support null safety.
-
-## 1.1.0-nullsafety
+## 2.0.0
 
 * Migrate to null safety.