DuckDuckGo: remove 5.64.0 (56400)

Outdated, failing build.

metadata/com.duckduckgo.mobile.android.yml

@@ -766,18 +766,6 @@ Builds:
     prebuild: sed -i -e 's/21.0.6113669/21.3.6528147/' app/build.gradle
     ndk: r21d
 
-  - versionName: 5.64.0
-    versionCode: 56400
-    commit: 5.64.0
-    submodules: true
-    gradle:
-      - yes
-    output: app/build/outputs/apk/release/duckduckgo-$$VERSION$$-release-unsigned.apk
-    rm:
-      - styleguide/ddg-settings.zip
-    prebuild: sed -i -e 's/21.0.6113669/21.3.6528147/' app/build.gradle
-    ndk: r21d
-
   - versionName: 5.65.0
     versionCode: 56500
     commit: 5.65.0