Android Crash on release mode

When android app is build with `def enableProguardInReleaseBuilds = true`, application crash on LibVosk initialiation with that error:

```
11-04 15:22:30.599 10918 11365 E AndroidRuntime: java.lang.UnsatisfiedLinkError: Can't obtain peer field ID for class com.sun.jna.Pointer
11-04 15:22:30.599 10918 11365 E AndroidRuntime: at com.sun.jna.Native.initIDs(Native Method)
11-04 15:22:30.599 10918 11365 E AndroidRuntime: at com.sun.jna.Native.(Unknown Source:333)
11-04 15:22:30.599 10918 11365 E AndroidRuntime: at org.vosk.LibVosk.(Unknown Source:4)
11-04 15:22:30.599 10918 11365 E AndroidRuntime: at org.vosk.Model.(Unknown Source:0)
11-04 15:22:30.599 10918 11365 E AndroidRuntime: at z7.k.i(Unknown Source:6)
11-04 15:22:30.599 10918 11365 E AndroidRuntime: at z7.k.b(Unknown Source:0)
11-04 15:22:30.599 10918 11365 E AndroidRuntime: at z7.h.run(Unknown Source:12)
11-04 15:22:30.599 10918 11365 E AndroidRuntime: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
11-04 15:22:30.599 10918 11365 E AndroidRuntime: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:644)
11-04 15:22:30.599 10918 11365 E AndroidRuntime: at java.lang.Thread.run(Thread.java:1012)
```

To **fix** it need to add rule `-keep class com.sun.jna.** { *; }` in `proguard-rules.pro` file.