message: fix(ionic4): remove landscape splash screens
diff: <icon density="xhdpi" src="resources/android/icon/drawable-xhdpi-icon.png" />
  <icon density="xxhdpi" src="resources/android/icon/drawable-xxhdpi-icon.png" />
  <icon density="xxxhdpi" src="resources/android/icon/drawable-xxxhdpi-icon.png" />
  - <splash density="land-ldpi" src="resources/android/splash/drawable-land-ldpi-screen.png" />
  - <splash density="land-mdpi" src="resources/android/splash/drawable-land-mdpi-screen.png" />
  - <splash density="land-hdpi" src="resources/android/splash/drawable-land-hdpi-screen.png" />
  - <splash density="land-xhdpi" src="resources/android/splash/drawable-land-xhdpi-screen.png" />
  - <splash density="land-xxhdpi" src="resources/android/splash/drawable-land-xxhdpi-screen.png" />
  - <splash density="land-xxxhdpi" src="resources/android/splash/drawable-land-xxxhdpi-screen.png" />
  <splash density="port-ldpi" src="resources/android/splash/drawable-port-ldpi-screen.png" />
  <splash density="port-mdpi" src="resources/android/splash/drawable-port-mdpi-screen.png" />
  <splash density="port-hdpi" src="resources/android/splash/drawable-port-hdpi-screen.png" />
  <splash height="1136" src="resources/ios/splash/Default-568h@2x~iphone.png" width="640" />
  <splash height="1334" src="resources/ios/splash/Default-667h.png" width="750" />
  <splash height="2208" src="resources/ios/splash/Default-736h.png" width="1242" />
  - <splash height="1242" src="resources/ios/splash/Default-Landscape-736h.png" width="2208" />
  - <splash height="1536" src="resources/ios/splash/Default-Landscape@2x~ipad.png" width="2048" />
  - <splash height="2048" src="resources/ios/splash/Default-Landscape@~ipadpro.png" width="2732" />
  - <splash height="768" src="resources/ios/splash/Default-Landscape~ipad.png" width="1024" />
  <splash height="2048" src="resources/ios/splash/Default-Portrait@2x~ipad.png" width="1536" />
  <splash height="2732" src="resources/ios/splash/Default-Portrait@~ipadpro.png" width="2048" />
  <splash height="1024" src="resources/ios/splash/Default-Portrait~ipad.png" width="768" />
  <plugin name="cordova-plugin-airgap-webview" spec="git+https://github.com/airgap-it/cordova-plugin-airgap-webview.git" />
  <plugin name="cordova-clipboard" spec="1.2.1" />
  <plugin name="cordova.plugins.diagnostic" spec="4.0.10" />
  - <engine name="android" spec="7.1.2" />
  <plugin name="cordova-plugin-app-version" spec="0.1.9" />
  - <engine name="ios" spec="~5.0.0" />
  + <engine name="android" spec="7.1.2" />
  + <engine name="ios" spec="5.0.1" />
  </widget>
  