whisper : add version function (#3289)

* whisper : add version function

This commit adds a version function to the whisper API.

The motivation for this is that it might be convenient to have a way to
programmatically check the version.

Example usage:
```c++
printf("Using whisper version: %s\n", whisper_version());
```
Will output:
```console
Using whisper version: 1.7.6
```

* examples : add version to android example CMakeLists.txt

CMakeLists.txt

@@ -178,6 +178,10 @@ get_directory_property(WHISPER_TRANSIENT_DEFINES COMPILE_DEFINITIONS)
 set_target_properties(whisper PROPERTIES PUBLIC_HEADER ${CMAKE_CURRENT_SOURCE_DIR}/include/whisper.h)
 install(TARGETS whisper LIBRARY PUBLIC_HEADER)
 
+target_compile_definitions(whisper PRIVATE
+    WHISPER_VERSION="${PROJECT_VERSION}"
+)
+
 configure_package_config_file(
         ${CMAKE_CURRENT_SOURCE_DIR}/cmake/whisper-config.cmake.in
         ${CMAKE_CURRENT_BINARY_DIR}/whisper-config.cmake