Maintenance: Remove no-op method (targetSDK 30)

https://developer.android.com/reference/android/widget/Toast#setGravity(int,%20int,%20int) : Starting from Android Build.VERSION_CODES#R, for apps targeting API level Build.VERSION_CODES#R or higher, this method is a no-op when called on text toasts. It resulted in an error entry in the logs each time the tool is switched.

- [x] Check that tool change toasts are shown correctly on all supported Android versions
- [x] Include a summary of the changes plus the relevant context
- [x] Choose the proper base branch (*develop*)
- [x] Verify that the changes generate no compiler or linter warnings
- [x] Perform a self-review of the changes
- [x] Verify to commit no other files than the intentionally changed ones
- [x] Stick to the project’s gitflow workflow
- [x] Verify that your changes do not have any conflicts with the base branch
- [x] After the PR, verify that all CI checks have passed

Paintroid/src/main/java/org/catrobat/paintroid/ui/MainActivityNavigator.kt

@@ -28,7 +28,6 @@ import android.graphics.Bitmap
 import android.net.Uri
 import android.os.Build
 import android.provider.OpenableColumns
-import android.view.Gravity
 import android.widget.Toast
 import androidx.appcompat.app.AppCompatDialogFragment
 import androidx.core.app.ActivityCompat
@@ -489,11 +488,9 @@ class MainActivityNavigator(
     override fun showToolChangeToast(offset: Int, idRes: Int) {
         var offset = offset
         val toolNameToast = ToastFactory.makeText(mainActivity, idRes, Toast.LENGTH_SHORT)
-        val gravity = Gravity.TOP or Gravity.CENTER
         if (mainActivity.resources.configuration.orientation == Configuration.ORIENTATION_LANDSCAPE) {
             offset = 0
         }
-        toolNameToast.setGravity(gravity, 0, offset)
         toolNameToast.show()
     }