Remove AlphaSlider in ColorPickerDialog as alpha colors are not supported by Android color contrast utils (fix #308)

Author: Shinokuni

app/src/main/java/com/readrops/app/feeds/color/ColorPickerDialog.kt

@@ -20,7 +20,6 @@ import androidx.compose.ui.graphics.RectangleShape
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.dp
-import com.github.skydoves.colorpicker.compose.AlphaSlider
 import com.github.skydoves.colorpicker.compose.BrightnessSlider
 import com.github.skydoves.colorpicker.compose.HsvColorPicker
 import com.github.skydoves.colorpicker.compose.rememberColorPickerController
@@ -58,14 +57,6 @@ fun ColorPickerDialog(
                 initialColor = color
             )
 
-            AlphaSlider(
-                modifier = Modifier
-                    .fillMaxWidth()
-                    .padding(vertical = MaterialTheme.spacing.shortSpacing)
-                    .height(24.dp),
-                controller = controller,
-            )
-
             BrightnessSlider(
                 modifier = Modifier
                     .fillMaxWidth()