Promote version 8.9.20-dev to version 8.9.20

Change-Id: Id5f135c7115fa0ed29ff95367502a73852da7b8f
diff --git a/src/main/java/com/android/tools/r8/Version.java b/src/main/java/com/android/tools/r8/Version.java
index db5e2b4..e9e7bf36 100644
--- a/src/main/java/com/android/tools/r8/Version.java
+++ b/src/main/java/com/android/tools/r8/Version.java
@@ -13,7 +13,7 @@
 
   // This field is accessed from release scripts using simple pattern matching.
   // Therefore, changing this field could break our release scripts.
-  public static final String LABEL = "8.9.20-dev";
+  public static final String LABEL = "8.9.20";
 
   private Version() {
   }