Update MaterialDatePicker to read colorSurface from correct context

Fixes issue where colorSurface from materialCalendarTheme is ignored

Resolves #838

PiperOrigin-RevId: 286194512
(cherry picked from commit 4e0a016)

Author: dsn5ft

lib/java/com/google/android/material/datepicker/MaterialDatePicker.java

@@ -164,7 +164,7 @@ public final Dialog onCreateDialog(@Nullable Bundle bundle) {
     fullscreen = isFullscreen(context);
     int surfaceColor =
         MaterialAttributes.resolveOrThrow(
-            getContext(), R.attr.colorSurface, MaterialDatePicker.class.getCanonicalName());
+            context, R.attr.colorSurface, MaterialDatePicker.class.getCanonicalName());
     background =
         new MaterialShapeDrawable(
             context,