refactor: revert PreferenceFooter to default theme colors

app/src/main/java/com/geeksville/mesh/ui/components/PreferenceFooter.kt

@@ -6,7 +6,6 @@ import androidx.compose.material.*
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
@@ -52,7 +51,6 @@ fun PreferenceFooter(
             enabled = enabled,
             onClick = onNegativeClicked,
             colors = ButtonDefaults.buttonColors(
-                backgroundColor = Color.Red.copy(alpha = 0.6f),
                 disabledContentColor = MaterialTheme.colors.onSurface.copy(alpha = ContentAlpha.disabled)
             )
         ) {
@@ -69,7 +67,6 @@ fun PreferenceFooter(
             enabled = enabled,
             onClick = onPositiveClicked,
             colors = ButtonDefaults.buttonColors(
-                backgroundColor = Color.Green.copy(alpha = 0.6f),
                 disabledContentColor = MaterialTheme.colors.onSurface.copy(alpha = ContentAlpha.disabled)
             )
         ) {