ci: manually point ANDROID_NDK_ROOT to latest supplied version

It seems the symlink to `ndk-bundle` and this environment variable
pointing to it have been removed to prevent the sdkmanager from failing,
when finding the SDK setup to be in an "indeterminate" state.  It is now
up to the users themselves to install an NDK through that tool or point
the right variables to a preinstalled "latest" NDK.

actions/runner-images#2689
actions/runner-images#5926

Author: MarijnS95

.github/workflows/ci.yml

@@ -5,6 +5,9 @@ on:
   push:
     branches: [master]
 
+env:
+  ANDROID_NDK_ROOT: ${{ env.ANDROID_NDK_LATEST_HOME }}
+
 jobs:
   Check_Formatting:
     runs-on: ubuntu-latest