Use NDK r27d instead of r29

Update Android build configuration to reference NDK r27d rather than r29. Adjusted android/README.md and android/android-env.sh to reflect the new default NDK version; NDK_HOME handling remains unchanged.

Author: FeodorFitsner

android/README.md

@@ -4,7 +4,7 @@ Scripts and CI jobs for building Python 3 for Android.
 
 * Can be run on both Linux and macOS.
 * Build Python 3.12 - specific or the last minor version.
-* Installs NDK r29 or use pre-installed one with path configured by `NDK_HOME` variable.
+* Installs NDK r27d or use pre-installed one with path configured by `NDK_HOME` variable.
 * Creates Python installation with a structure suitable for https://github.com/flet-dev/mobile-forge
 
 ## Usage

android/android-env.sh

@@ -5,7 +5,7 @@
 : ${api_level:=24}  # Minimum Android API level the build will run on
 : ${PREFIX:-}  # Path in which to find required libraries
 
-NDK_VERSION=r29
+NDK_VERSION=r27d
 
 # Print all messages on stderr so they're visible when running within build-wheel.
 log() {